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Timestamp: 2019-04-20 08:53:31+00:00

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This study was conducted in cooperation with the U.S. Department of Transportation, Federal Highway Administration. Studded tires have generated much controversy over the years; a number of states have banned them, while others, including Washington, have restricted their use and passed legislation to require lighter-weight studs. This report reviews recent studies that have addressed the performance and safety of the current generation of studded tires as well as the new “studless” winter tires on late-model vehicles. The well-documented correlation between studded tires and pavement wear was not the focus of this work. The issues surrounding studded tire performance and safety are complex. From the standpoint of traction alone, studded tires, when new, often provide some benefit over other tire types on ice-covered roads when the temperature is near freezing. However, the advent of the new studless tires has diminished the marginal benefit, and recent studies suggest that the infrequent, narrow range of conditions necessary for benefit from studded tires may not outweigh their detrimental effect on traction in dry or wet conditions on certain pavement types. In addition, a host of primary and secondary safety factors are related to studded tire use, many of which are very difficult to quantify, including facets of driver behavior and safety perception.
necessarily reflect the official views or policies of the Washington State Transportation Commission, Department of Transportation, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation.
Although a substantial volume of research has investigated the negative impact of studded tires on pavement. this report does not concentrate on pavement wear issues. including the parameters that are used to define traction performance. Rather. the conditions under which studded tires are compared with other tires. have placed restrictions on their use and passed recent legislation requiring lighter-weight studs to reduce pavement wear. including the introduction of suspended particulate matter (dust) from roadway wear. the increase in fuel ix .EXECUTIVE SUMMARY This study presents an extensive review of publications documenting recent research on the performance and safety of studded tires. the potential for improved traction characteristics on roadways “roughened” by studded tire use. as well as those equipped with the new “studless” winter tires such as the “Blizzak” made by Bridgestone/Firestone. reduced vehicle control on roadways rutted by stud wear. the cost of studded tires in comparison with new studless winter tires. There are also a host of secondary effects. The issues surrounding the use of studded tires are very complex. the “safety” of studded tires as measured by traffic incident data. A number of states have banned them. while others. and driver behavior while using studded tires based on drivers’ perception of safety. the focus of this work was to review the latest findings regarding the performance of late-model vehicles equipped with the current generation of studded tires. The use of studded tires has been controversial over the years. involving not just the obvious competing advantages and disadvantages of improved icy-road traction performance versus the costly impact of pavement damage. including Washington. There are many factors to consider.
since the early 1990s. where x . the increment usually was small. Studded tires produce their best traction on snow or ice near the freezing mark and lose proportionately more of their tractive ability at lower temperatures than do studless or all-season tires. the traction benefit for studded tires is primarily evident on clear ice near the freezing mark. The traction of studded tires is slightly superior to studless tires only under an ever-narrowing set of circumstances. and a discussion of the traction performance characteristics of studded versus non-studded tires under varying conditions. The precise environmental conditions under which studded tires provide a traction benefit are relatively rare. The maximum frictional gain (in comparison to nonstudded (not studless) tires) is found for new studded tires on smooth ice. CONCLUSIONS 1. and with the advent of the new “studless” tire. such as the Blizzak. a discussion of the newer studded and “studless” winter tires. studded tires performed as well as or worse than the Blizzak tire. For the majority of test results reviewed for snow. and the possible trade-off in the use of traditional snow-clearing methods. a condition whose occurrence is limited. The broader issue of safety is also addressed through presentation of the many complex issues surrounding studded tire use that have been raised by recent research worldwide. 3. With less aggressive (lightweight) studs being mandated. and for ice at lower temperatures.consumption for studded versus studless tires. For those conditions in which studded tires provided better traction than studless tires. This report presents a brief history of studded tires and their usage. 2.
However. controllability. the single best indicator of tire performance is braking distance and deceleration. studless. Studded tires reduce the difference in friction factor between optimum-slip and locked-wheel braking in comparison to non-studded tires. 5. when averaged across several vehicles. as the temperature drops. including braking. This may reduce the risk of drivers misjudging the necessary braking distance and may improve the braking potential for anti-lock brakes. studded. as the studs wear. which in turn were 8 percent shorter than for all-season tires. and all-season tires performed nearly equally on snow. In one set of stopping distance tests in Alaska. Traction performance can be characterized in many ways. especially for braking on both packed snow and ice in comparison to studded tires (which were second) and all-season tires (which were last). and grade climbing. stopping distances for studded tires were 15 percent shorter than for Blizzaks. studless Blizzak tires offered the best traction performance. xi . acceleration. 6. Though all factors are important.they have been shown to provide up to 100 percent gain in certain tests. 8. the relative frictional gain of studded tires diminishes or becomes negative on roughened ice. cornering. In another set of tests in Alaska. 7. such as yaw instability. On ice. other controllability penalties. The use of two studded tires on the front of a vehicle produced stopping traction results on snow and ice that were about halfway between the result of four studded tires and four all-season tires. 4. or if the comparison is made with studless tires. should be considered. However.
(1. On bare pavement. excessive road spray. xii . the frictional effect from the studs becomes negligible. and premature damage to pavement markings. for asphalt. There is not consensus on these points: 1) drivers with studded tires care more about safety.039 in. 14. to 0.043 in.9. there is little difference in stopping distance between studded and non-studded tires.6 mm). A number of driver behavior issues have been postulated that tend to affect the judgment of studded tire effectiveness. 10.024 in. hence they drive more safely. and 3) drivers with non-studded tires avoid driving when weather is severe. This is especially true for concrete. 13. 12.1 mm). 2) they drive faster (because of a false sense of security or confidence). When stud protrusion diminishes to 0. hydroplaning on accumulated water in the ruts. Pavement rutting caused by accelerated wear from studded tires can cause the dangerous conditions of tramlining. Studded tires may lose more of their tractive ability over time (from stud wear) than studless tires. (0. The roughening of ice and pavement from studded tires provides a safety benefit for all vehicles (with and without studs) by helping to prevent formation of smooth. A Norwegian study concluded that the use of studded tires tends to reduce the accident rate by a small amount – from 1 to 10 percent.01. Tractive performance of studded tires is sensitive to stud wear. Tire tread wear (on studded tires) has relatively little frictional effect if stud protrusion is maintained at 0. 11. studded tires tend to have poorer traction performance than other tire types. glare ice.
xiii .2 percent) over non-studded tires on bare roadways. Studded tires increase fuel consumption by a small amount (~1. The cost of studless tires is significantly higher than studded tires—by approximately 50 percent. But the other effects of unevenness.15. snow. 17. 16. and ice are far more significant than this factor and can increase fuel consumption by 15 percent. Suspended particulate matter from pavement dust created by studded tires and noise from studded tires are health concerns in heavily traveled urban areas.
this study focuses on the performance on various road surface conditions of studded tires as compared with that of other common winter tires.1. Numerous recent studies have documented the pavement wear caused by studded tires. Legislation in many states has banned or limited the use of studded tires and has mandated less aggressive studs in an effort to reduce costly pavement damage (see appendices A and B). However. Rather. They quickly became popular in the northern climes because they provided the motorist with a built-in traction aid without the installation headaches required by temporary aids such as tire chains. and vehicles with front-wheel drive. In addition to performance data. particularly from the past 10 years. STUDY APPROACH The objectives of this study were accomplished by comprehensively reviewing literature reporting on studded tire performance research that was performed in the 1 . and anti-lock brakes. studless winter tires. Studded tires are convenient. INTRODUCTION Studded tires were introduced in the United States in the early 1960s. and they have been well accepted by the general public as a means of enhancing mobility. so these issues will not be presented here in detail. studded tires have long been the source of considerable controversy. It encompasses a review of recent literature. a review of studies that examined the complexities of evaluating the safety of studded tires is also presented. that documents studies relevant to the new generation of lighter weight studs. including all season radials and the new “studless” winter tires. relatively quiet and comfortable (in comparison to tire chains). four-wheel drive.
United States.and fourwheel-drive vehicles. 2 . mostly from the 1990s. the focus was on more recent data. Canada. and Japan. and studless winter tires. Europe. This research also sought data on the effects of recent developments on vehicle traction. Though some of the foundations for this study were developed from the 1960s through the 1980s. including the more widespread use of front.
a flange at the base of the stud jacket holds it in place. or insert is situated within the jacket and protrudes from the tire to make contact with the pavement (Figure 1). Conventional studs in the 1960s were approximately 0. In this way. filling any space between the jacket and the rubber. with a protrusion of about 0. both the weight and protrusion have been reduced. The outside part of the stud is known as the stud jacket or sleeve. the rubber secures the jacket in place (Angerinos et al. as stud weight and protrusion length were shown to be significant factors in pavement wear rates. pin. and in Alaska. (7.087 in. Currently. 1999).2 mm). After insertion of a tire stud (jacket and pin) into the tire. studded tire use approached 30 percent of passenger vehicles by 1972. 1999).8 mm) long. Since the 1970s. Montana. approximately 10 percent of passenger vehicles in western Washington use two or more studded tires and approximately 32 percent of passenger vehicles in eastern Washington use two or more studded tires. weight. studded tires became popular with drivers across the U. and Vermont approximately 60 percent of passenger vehicles used studded tires (Malik 2000).S. The advent of the Controlled Protrusion (CP) 3 .307 in.2. In many states. a “breakin” period occurs during which time the tire rubber completely surrounds the stud jacket. and composition over the years. BACKGROUND HISTORY AND COMPOSITION OF TIRE STUDS After their introduction in 1963. The stud core. In Spokane. approximately 56 percent of passenger vehicles use two or more studded tires (Angerinos et al. (2. The tire stud consists of two basic parts that have varied in size.
081 oz. weighs 0.0 to 1.S. (2. Typical First-Generation Stud Profile (Angerinos et al.7 to 1.stud allowed for nearly a 40 percent reduction in pin protrusion to 0. Figure 1.059 to 0.067 oz. today. 1999) 4 .039 to 0. (1. (1.3 grams). while the typical CP stud.9 grams) (Angerinos 1999). 1999) First-Generation Stud CP Stud Figure 2.5 mm) by using a tapered pin that is able to move back into the stud jacket as the tire rubber is worn (Figure 2). which is the only stud in use in the U. Comparison of First-Generation Stud with Controlled Protrusion (CP) Stud (Angerinos et al.059 in. The weight of the conventional stud from the 1960s averaged approximately 0.
while the highest was found in Spokane (56 percent). These rates were determined by moving traffic counts.033 oz.In the Scandinavian countries. The survey sampled parking lots and garages in 14 locations. A WSDOT survey conducted during the winter of 1996-1997 showed that on average. The earliest data (NCHRP 1975) showed widely varying usage numbers across the northern United States and Canada.2 to 1.059 in./0. additional efforts have been made to reduce stud protrusion and weight.5 percent in 1989 (Table 1) (Malik 2000).1 grams). STUDDED TIRE USAGE It is difficult both to obtain accurate estimates of the usage of studded tires in cold weather climates and to determine whether the use of studded tires is increasing or decreasing.039 oz. Studs there now range in length from 0. in which vehicles equipped with studded 5 . and 32 percent used them in the eastern portion of the state (based on two studded tires per vehicle) (Angerinos 1999). (1.7 gram). The lowest stud usage was observed in Puyallup (6 percent). most perceived that studded tire use had declined and that winter tire use had dropped to less than 10 percent for passenger cars (Angerinos 1999). Washington usage was 35 percent in that survey.025 oz.5 mm) and weigh approximately 0. According to a 1995 survey of the 25 northern states and four Canadian provinces. ranging from 10 percent in Oregon to 61 percent in Alaska./0.3 percent in 1974 to 3. 10 percent of passenger vehicles used studded tires in the western portion of Washington. Historical studded tire usage rates in Oregon show that usage was fairly constant or declined somewhat from 9.95 gram) (Brunette 1995). as well as those with a lightweight metal jacket (0. (1. Testing in Scandinavia has shown reduced wear effects for studs with a lightweight plastic jacket (0.047 to 0. The most detailed examination of usage rates was found in Oregon.
bordered by Zone 1 to west. Early surveys could not distinguish this difference.2 6.4 1.3 11. Then.0 24.8 11.7% 1983-4 1.0 3. Mt.0% 2.5 percent.7 2.6 6. 1989 1.usage rates appeared to climb. Results showed that approximately half of vehicles in Oregon that were equipped with studded tires used them on both axles. California state line to south.1% 5. 1990 Parking Lot 1.tires were distinguished audibly from those that were not.5 14.8 5.0 9.2% 1983-4 3. A 1990 visual parking lot survey showed an increase in usage to 11.5% 3.5% Zone 1: Entire state coastal zone. Some of this may have been attributable to an increase in the number of vehicles that had studded tires on both axles instead of one.7 14. midway between Portland and Salem to north.0 11. Zone 3: Northwest quadrant of state. This survey was conducted primarily to determine the effect of studded tires on pavement wear. Hood to east.0 15. a considerable increase from the 1970s when the 6 . Zone 1 to west. in 1990. including Portland.4% Mar.4 5.5 8.3 10. the usage rates were determined on a per-vehicle basis. Historic Studded Tire Use Estimates (Percentage of Vehicles) for Oregon (Malik 2000) Zone 1 2 3 4 Statewide 1973-74 1. 1990 Mar. Table 1. Washington state line to north Zone 4: Everything else Extensive telephone and parking lot surveys conducted in 1995 and 1996 on behalf of the Oregon Department of Transportation indicated that studded tire use varied widely depending on the month and region being surveyed (Malik 2000).2 6. not just the number of vehicles. Hence. This technique provided a means for developing an effective studded tires usage rate by accounting for the number of axles that used studded tires.8% 0.5% 4.9% 2. 10-15 miles inland from coast Zone 2: Western valley bordered by Cascase range to east.6% Dec.6% 3.
depending on who conducted the survey and how it as performed. Hence. For the winter driving season of November through April. No data have been found to assess the usage rates of studless winter tires such as the Bridgestone/Firestone Blizzak. it was necessary to account for the effective studded tire usage on a per-axle basis. the average effective studded tire usage rate statewide in Oregon ranged from about 16 percent to 23.majority of vehicles installed studded tires only on the driving axle.5 percent. 7 .
Some of the metrics include straight line braking acceleration cornering controllability grade climbing. truck. including the following: initial speed (for braking tests) tire type (studded. rear-wheel drive.3. though intuitively related. four-wheel drive) vehicle weight distribution brake system type (ABS or non-ABS) roadway pavement type and condition 8 . non-studded. A multitude of variables will affect results. as such. SUV) vehicle drive configuration (front-wheel drive. Determination of studded versus non-studded tire performance can be measured in a number of different ways. studless) number of studded tires (two or four) vehicle type (automobile. will be dealt with independently. which is more quantitative. WINTER TIRE PERFORMANCE Studded tire performance and safety. was the focus of this work. are two different topics and. The performance of studded tires relative to non-studded tires.
including braking. The traction performance of tires is primarily a function of the frictional characteristics between the tire and the driving surface. most of these factors have been tested individually and in various combinations by a variety of researchers over many years. smooth ice. loose snow. This dimensionless value. and to our knowledge. studded tires do not necessarily shorten stopping distances. Though this occurs under certain slippery conditions involving ice. FRICTIONAL CHARACTERISTICS One measure of tire performance is through tire frictional characteristics. acceleration. for betterment of control during braking. tests over the years have shown that stopping distances are often increased on dry or wet pavement surfaces. studroughened ice) temperature (above freezing. is useful for predicting many facets of vehicle performance. and cornering. It has further been shown that under certain cold temperature conditions on icy roadways. has not been done. wet. Studded tires were obviously intended to increase friction between tire and a driving surface. packed snow. and cornering. near freezing. Instead. often represented by the coefficient of friction between the tire and roadway surface. acceleration. well below freezing). To develop a comprehensive test matrix that would consider the effect of each of these variables would be a monumental task. The static coefficient of friction is the ratio of the horizontal force that can be sustained by the tire 9 .roadway surface condition (dry. The results of some of those studies are presented below. though relatively theoretical.
it is difficult to measure in a practical sense. but relative values for tires within each performance category should be comparable. or drag factor. TEMPERATURE EFFECTS AND ROAD CONDITIONS Studs are most effective on ice at or near 32 degrees F (0 degrees C) and lose their efficacy as temperatures drop and the ice becomes too hard for the studs to grip or when temperatures rise and ice melts to slush or wet pavement. or cornering divided by the vertical load (weight) on the tire. Connecticut. Hence.to the vertical force (usually weight) on the tire. Friction factors for a tire undergoing braking. Because coefficient of friction represents a measure of only the specific interaction between the tire and roadway. show that the roads are icy only 12 to 13 percent of the time. other vehicle and environmental factors enter into the actual measurement of vehicle/roadway frictional performance. and Minnesota are shown in Table 2 (Lu 1994). and cornering may be different. Another study in Alaska stated that because of the temperature limitations on the effectiveness of studded tires (between 0 and 32 degrees F (–18 and 0 10 . it has been estimated that ice at or near freezing exists only 1 percent of the time in the State of Washington (WSDOT website). However. is sometimes used to represent the cumulative effect of all these variables and can be interpreted as the “effective” coefficient of friction. Friction factor can be defined as the force that can be generated by a tire (vehicle) in braking. both of which have harsh winters. Some references use the terms coefficient of friction and friction factor interchangeably. Average winter road conditions in the states of Alaska. acceleration. These data for Alaska and Minnesota. accelerating. the term friction factor. that will be the case here also.
in comparison with studless tires. was likely to be considerably less than 13 percent. 11 .degrees C)). no distinction was drawn between ice near the freezing point and ice at lower temperatures. Because studded tires. Again.15 percent. their capabilities can only be used for 6 percent of the winter (Alaska Studded Tire Study 1973). it is difficult to predict which tire will perform better unless temperature is part of the equation. Average Winter Road Surface Conditions (Lu 1994) State Dry/Wet Pavement (%) 65 96.15 percent of the vehicle miles traveled. The same source named a similar study in Ontario that examined average winter conditions for two years in the early 1970s. the total proportion of vehicle miles traveled on ice near the freezing point.5 75 Snow/Packed Snow (%) 22. Table 2. Hence.5 13 Alaska Connecticut Minnesota An older study reported that about 13 percent of all vehicle travel in Minnesota was on ice or hard-packed snow (NCHRP 1975). though no distinction was drawn between ice and hard-packed snow. The temperature sensitivity of traction performance complicates the evaluation of studded versus non-studded or studless tires.6 3 12 Icy Pavement (%) 12. nor for icy roads near the freezing point.4 0. so the traction benefits from studded tires would likely accrue for even fewer miles than the reported 2. tend to show advantages on ice near freezing and are at a disadvantage at temperatures well below freezing. where studded tires have some recognized effectiveness. That study showed that icy conditions prevailed for an average of 2.
Traction tests involved measuring the traction force while spinning the drive wheels of a vehicle that was either stationary or traveling. Locked wheel braking tests measured tire/roadway friction at 20 mph (32 kph). snowy. and anti-lock brakes. Results were similar for the traction and controllability tests. Researchers performed tests and gathered published data to substantiate analytical estimates of friction factors for various tire and vehicle configurations. Their values measured braking. and “controllability” of the test vehicles equipped with standard highway tires. or wet surfaces (Hayhoe and Kopac 1981). studded tires. Controllability values represented lateral tire frictional forces. snow tires. driving traction. Results showed that studded tires had slightly better locked-wheel braking performance (higher friction factor) on ice than highway or snow tires but were identical in performance to snow tires on snowy or wet surfaces. 12 . The results of the testing and analysis are summarized in Table 3. four-wheel drive.PENNSYLVANIA TRANSPORTATION INSTITUTE STUDY A study performed by the Pennsylvania Transportation Institute reported a comparison of friction factors for vehicles fitted with various traction aids on icy. Not surprisingly. four-wheel drive was vastly superior for traction and controllability but offered no improvement in braking. Anti-lock brakes showed benefit for controllability tests but not for locked-wheel braking or traction maneuvers.
175 0.19 0.15 0.15 0.27 0.4 0.03 Wet 0.09 0.4 0.175 0.12 0.19 Controllability Ice Snow Wet 0.08 0.08 0.08 0.19 0.4 For rear wheel drive vehicle.27 0.175 0.16 0.12 0.4 0. and Conditions1 (Hayhoe 1981) Locked-Wheel Braking Ice Snow Wet 0. Vehicle Friction Factors for Various Vehicle and Traction Aid Configurations.08 0.055 0.19 0.3 0.4 0.08 0.15 0.4 0.024 Traction Snow 0.4 0.13 0.024 0.19 0.15 0.4 0.8 0.03 0.19 0.08 1 Highway Tires Snow Tires (on rear only) Steel Tire Chains (on rear only) Studded Snow Tires (on rear only) Four-wheel Drive Anti-lock Brakes (4-wheel systems) Anti-lock Brakes (2-wheel systems) Ice 0.4 0.055 0.4 0.024 0.19 0.17 0.064 0.4 0.37 0.032 0. ice temperature 25o F 13 .03 0. Maneuvers.08 0. except where noted.Table 3.09 0.19 0.6 0.024 0.16 0.175 0.15 0.8 0.3 0.23 0.
02-0.2-0. and maximum cornering.27 0.08 14 .09-0.12 0. studded tires.05 Friction Gain due to Studs 0.16-0.05-0.13 0.8 mm) were tested.33 0.27 0.11 0.14-0.SWEDISH ROAD AND TRAFFIC INSTITUTE STUDY Another comparison of the frictional characteristics of studded and non-studded tires was performed by the Swedish Road and Traffic Institute (VTI) in 1988 (Nordstrom and Samuelsson 1991).26 0.04) 0.07 (-0. A partial summary of test results can be found in Table 4.24-0.19 0.04-0. tire wear.09 0. Table 4.13 0.38 0.14-0.25 0.043 to 0.07 0.10-0.15-0.36-0.12-0.12-0.17 0.07 0.12 0.00-0.10-0.10-0.2o to 6. Friction Coefficients for Studded and Non-Studded Tires Under Various Conditions (based on Nordstrom and Samuelsson 1991) Friction Coefficient Temperature: 32oF (0oC) Smooth Ice Optimum Slip Locked Wheel Maximum Cornering Temperature: 32oF (0oC) Stud-Roughened Ice Optimum Slip Locked Wheel Temperature: 30. locked-wheel braking.12-0.14-0.1-1.02-0.8oF (-1 to -14oC) Smooth Ice Optimum Slip Locked Wheel Maximum Cornering Temperature: : 30.02-0.21-0.26 0.21 0.19 0.10 0.02-0.20 (-0. This research compared the frictional differences between studded tires and non-studded winter tires (intended to be studded).44 0.25 0. (1.00-0.21-0. fitted with 105 to 123 studs each.23 0. ice condition (smooth versus stud-roughened).18-0.2o to 6.14 0. It also considered the effect of stud protrusion (which includes the effect of stud wear).8oF (-1 to -14oC) Stud-Roughened Ice Optimum Slip Locked Wheel Non-Studded Tire Studded Tire 0.05-0. New. Tests included optimum-slip braking.03) 0.02-0. and with stud protrusion of 0.070 in.36-0.09-0. and ice temperature.
On 32 degree F (0 degree C) ice roughened by studs. Locked-wheel braking is when all four wheels are arrested. both for maximizing deceleration and for enhancing vehicle stability and control.04. The purpose of ABS is to automatically optimize slip while braking. Typically.00 to 0.11. non-studded to studded tires was –0. the greatest effective gain in friction coefficient (0.36 to 0.10) occurred for studded tires undergoing optimum-slip braking. For example. the friction gain was higher for studded tires (0. the friction coefficient for new. Under certain conditions. This occurred on smooth ice at 32 degrees F (0 degrees C).20-0.38. non-studded tires under optimum-slip braking was 0. the frictional change from new. on ice roughened by studs at temperatures between 14 and 18 degrees F (–10 and –8 degrees C). the degree of deceleration achieved under such conditions is usually not as great as with optimum-slip braking. but the baseline friction coefficient was lower for non-studded tires (0. 15 .23). Key findings from the VTI study included the following: For the comparison of new studded with non-studded tires. The friction gain due to studs was modest at 0. particularly when temperatures were below the freezing mark. where the friction coefficient for non-studded tires was 0. optimum slip occurs when there is between 10 and 15 percent wheel slippage (rather than 100 percent slippage. For locked wheel braking under the same conditions. a benefit of nearly 100 percent.02 to 0.07.13).09 to 0. there was no frictional gain from studded tires.In reviewing Table 4. note that optimum slip is defined as the degree of brake application necessary to achieve maximum deceleration (or maximum coefficient of friction).02-0. which occurs under locked-wheel braking).
197 in. In contrast. this benefit greatly diminished when ice temperatures dropped below freezing.039 to 0. On 32 degree F (0 degree C) “wet” ice. Hence. On smooth ice under optimal-slip braking. stud protrusion has much more influence than tire wear under these circumstances. studded tires worn to 0. or on colder ice with surface contamination from snow or ice powder. perhaps the most prolific was Jian John Lu. Friction generally increased with increasing ice roughness.0-1. the effect of worn tires is not nearly so pronounced. This could reduce the risk of misjudgment of necessary braking distance and may improve the braking potential for anti-lock brakes. Alaska. (0. (5 mm) tread depth with stud protrusion of 0. Lu’s work was performed in the mid 1990s. (1. Mr. clear ice near 32 degrees F (0 degrees C). The highlights of his work.The frictional effect of studs becomes negligible when stud protrusion drops to about 0. the friction factor for both studded and non-studded tires at least doubled on roadways with roughened ice as compared with smooth ice.1 mm) yield friction values similar to that of a new studded tire under the same conditions. of the Transportation Research Center at the University of Fairbanks. However.6 mm). which include test data as well as a review of data from other 16 . Studded tires reduce the difference in friction factor between optimum-slip and locked-wheel braking more than do non-studded tires. 1994 ALASKA STUDIES Of the researchers of studded tire performance over the past 10 to 15 years.043 in.024 in. This suggests a benefit to traction for vehicles not equipped with studded tires when they travel on icy roads previously traversed by vehicles with studded tires. Studded tires are most beneficial when used on wet.
in the case of the Bridgestone Blizzak. Lu is particularly relevant to the present study undertaken by the State of Washington because it represents a recent examination of the performance issues of the latest generation of studded and studless radial tires on contemporary vehicles with such characteristics as front-wheel drive and anti-lock brakes. These tires incorporate an aggressive. The Blizzak is one of the more popular alternatives to studded tires. developed in the early 1990s. Tests were conducted by the University of Alaska at Fairbanks in the spring of 1994 (Lu 1994). Studless winter tires. micro-bubbles that provide tiny gripping edges on ice*.sources. The work performed by Mr. The tests compared the effects of the Bridgestone/Firestone “Blizzak” tire. with conventional studded tires and all-season tires. one of a series of modern “studless” snow tires developed for increased winter traction. deep tread design in a soft rubber compound with multiple sipes and. represent a new class of tire dedicated to winter travel. will be presented here along with findings from other sources. and many studies have sought to compare the performance of the Blizzak with that of studded tires on ice and packed snow surfaces. * Other studless winter tires (Q-rated/Snowflake symbol) Bridgestone Blizzak MZ-01 Bridgestone Blizzak MZ-02 Bridgestone Blizzak WS-15 (original) Bridgestone Blizzak WS-50 Bridgestone Blizzak W965 (Light Truck) Bridgestone Winter Dueler DM-Z2 (Light Truck) Dunlop Graspic DS-1 Dunlop Graspic HS1 / HS2 Dunlop Grandtrek SJ4 (Light Truck) Goodyear Ultra Grip Ice Michelin Arctic-Alpin Michelin 4X4 Alpin (Light Truck) Pirelli Winter Ice Asimmetrico Pirelli Winter 210 Performance Ice Yokohama Guardex 600 Yokohama Guardex RV F340 17 .
0) Average 50.5 (19.6) 105.5 (32.7 (46.1) 122. and 3) a rear-wheel-drive Chevrolet Caprice with ABS.5) 152.0 (31.3) 127.0) N/A N/A N/A 16.5) 2 Wheel Rear Wheel Drive Pickup Drive Car 79. 2) a two-wheel-drive.2) 16.6 (5.Tests were conducted at the Fairbanks International Airport under conditions of packed snow.2) 118.2) 116.1 (19.3 (19.9) 106.9) 69.1 (19.0 (5. results are shown in tables 5 and 6.4 (39.4 (18.5 (39.4) 64.2) 68. Stopping distances and starting traction were recorded and averaged.2) 16.4 (17. the studded tires were superior.1) 64.0 (37.5) 57. while the stopping distances of the all-season radials were 8 percent longer than the Blizzaks. ice.9) 17.5) 63.4) 84.5 (35.9) 64.0) Note: all vehicles equipped with ABS Stopping distance results averaged across the three vehicles showed that on packed snow there was little to distinguish one tire from another. Alaska (based on Lu 1994) Front Wheel Drive Car Packed Snow Surface Blizzak Tire Studded Tire All-Season Tire Icy Surface Blizzak Tire Studded Tire All-Season Tire 62.6 (20.7 (35. and Bare Pavement Surfaces in Fairbanks.6) 64.0 (38.3 (4.7) 128. and bare pavement using 1) a front-wheel-drive Chevrolet Lumina equipped with anti-lock brakes (ABS). Table 5. For bare pavement.7 (15.0 (19. Stopping Distances (feet (m)) on Packed Snow. the stopping distances of the three tires (tested only on the pickup) were 18 .5) 128.3 (24.6 (5.5) 59.3 (4.0) 117. showing 15 percent shorter stopping distances than the Blizzaks. Icy. full-size Chevrolet pickup truck equipped with ABS.2 (18.1 (32.0 (25.1) Bare Pavement Surface Blizzak Tire Studded Tire All-Season Tire N/A N/A N/A 16.2 (36.0 (5.0 (21.9) 17. On ice.3) 104.
These differences may not be significant.6 seconds.49 12. On ice. Icy. But on the pickup. The longest stopping distance was for the studded tires. Starting Traction Tests (Time to Reach 25 mph (40. the studded tires and Blizzaks were very similar.41 11. Alaska (Lu 1994) Front Wheel Drive Car Packed Snow Surface Blizzak Tire 8.88 sec Studded Tire 9.49 seconds. Table 6.94 13 12.42 10.3 km/h). and both showed superior traction 19 .very similar.99 Average 9.12 and 9. the studded tires provided traction very similar to that of the Blizzaks.68 N/A N/A N/A 3.7 9. at 10. traction was defined by the time (in seconds) it took for the vehicle to accelerate from a standstill to 25 mph (40.08 17. and Bare Pavement Surfaces in Fairbanks.06 Icy Surface Blizzak Tire Studded Tire All-Season Tire Bare Pavement Surface Blizzak Tire Studded Tire All-Season Tire 2 Wheel Rear Wheel Drive Pickup Drive Car 9.3 km/h)) (sec) on Packed Snow. Results.27 All-Season Tire 10.74 3. All the tests were relatively vehicle and driver dependent.73 N/A N/A N/A 3.52 3. but only by 2 percent over the all-season radials and 5 percent over the Blizzaks. at 9.94 12.12 10.86 16.and rear-drive cars equipped with studded tires held a clear advantage over the Blizzaks and all-season tires.73 Note: all vehicles equipped with ABS For the starting traction tests.5 sec 8.57 10. The all-season tires were slightly behind.52 3.74 3.41 sec 9.53 10.01 18.53 13. showed that for packed snow. shown in Table 6.63 19. respectively.03 14.6 sec 9. front. which is marginally significant.
7 (22.7) Studded Tires 15.1 to 0. Maximum Speeds During Cornering (mph (kp/h)) (based on Lu 1994) 25-ft (7.2 (22. It is not clear whether this difference is significant. The studded and all-season tires had nearly identical results.7 m) and 50 ft (15. however.to the all-season tires by about 40 percent. and not likely significant.3 (16. Tests were also conducted by the University of Alaska at Fairbanks to investigate cornering and hill climbing ability.8) 13. the vehicles were operated on curves with radii of 25 ft (7.9) 13. Table 7. For the cornering tests.2 (27. On bare pavement. and on ice was 0. Lateral acceleration was measured with instrumentation.6) Ice on Pavement 14. only the pickup was used.3 km/h) were about 18 percent longer than those for studded tires.2.40. and maximum cornering speeds were calculated from the data.0) 50-ft (15.9 (17.2) 9.9 (25. the Blizzak traction times to reach 25 mph (40.8) 10.7 m) Curve Packed Snow Ice on Pavement 10.6 (21.8 (15.0 Blizzak Tires 12. however.1 (16. while the Blizzak was approximately 7 percent faster.5) All-Season Tires 11.4 m) while lateral acceleration was recorded.7) 20 . On the average for all vehicles.8 (19.1 (19.4 m) Curve Packed Snow Blizzak Tires 17.25 to 0.5) Studded Tires 10. and the Blizzak generally had the highest. Variations were not large. Results summarized in Table 7 show that studded tires generally had the lowest cornering speeds. Maximum lateral acceleration on snow was found to be 0.6) All-Season Tires 17.2 (27. but about 13 percent less than for the all-season tires.
Tests determined that both the studded snow tires and the Blizzaks had similar grade climbing capability in packed snow. but the studded tires had a slight advantage in icy conditions. ice on pavement. Maximum starting grades are summarized in Table 8 for tests on packed snow. and lake ice. Table 8. Maximum Starting Grades (percent) (Lu 1994) Packed Snow Fairbanks Results Blizzak Tires Studded Tires All-Season Tires Anchorage Results Blizzak Tires Studded Tires All-Season Tires Ice on Pavement 11% 12 10 16% 16 15 18 16 15 10 11 N/A 1995 ALASKA STUDIES As a continuation of the 1994 research project in Alaska. including 1) the effects of used (worn) winter tires on traction performance 2) the performance of lightweight studded tires 21 . additional testing was performed there in 1995 (Lu 1995) to validate previous results and to consider other factors. Both the studded snow tires and the Blizzaks were superior to the all-season tires for grade climbing.Gradability was analytically determined by measuring the longitudinal acceleration during traction tests in both Anchorage and Fairbanks.
a full-sized. The purpose of the first task was to explore the effect of tire wear on braking and starting traction. For all tasks. The first task involved traction performance tests on snowy and icy surfaces with the same tires that had been tested in 1994 (which were new at that time).3 km/h). stopping distance and maximum deceleration were measured after brakes were applied (in an effort to lock the brakes) on vehicles traveling 25 mph (40. the shortest stopping distance for the snowy surface was from the Blizzaks.3) the performance of a front-drive car and a rear-drive pickup with studded tires on only the two front wheels 4) the effect of tire wear and pavement surface temperature on traction performance 5) vehicle controllability (lateral traction) performance tests 6) the effect of vehicle type on traction performance. which were 9 to 13 percent better than the studded tires and 18 to 24 percent better than the all-season tires. The tires had accrued more than 1000 miles (1610 kilometers) of wear since they were originally tested in 1994. Alaska. to more closely simulate real roadway conditions. When results for the first task were averaged for all three vehicles. the vehicles tested included a Chevrolet Lumina without ABS. tests for this study were primarily conducted on roads and parking lots around Fairbanks. two-wheel-drive Chevrolet pickup truck with ABS on only the rear wheels. For the braking traction tests. which were mostly conducted on airport taxiways. 22 . The air temperature during testing was reported to be below 10 degrees F (-12 degrees C). and a rear-wheel-drive Chevrolet Caprice with four-wheel ABS. Unlike the tests conducted in 1994.
9) Pickup 72.9) 81.6 (31.1) Caprice 50.2 (15.5) 89. but both were approximately 25 percent better than the all-season tires.5 (34. corresponded predictably to the braking traction results and hence are not presented here.5 (22.6 (26.3) 63. Table 9 and Figure 3 show the results of these tests.9 (21.2 (27.2 (21.1) 109.8) 78.1 (23.3 (25. Stopping Distances (m) of Test Tires with All Vehicle Types Combined (Lu 1995) 23 .7) 128.2) 88.1) 87.7 (25.8 (23.4) 104.8) 90.9 (33.6 (26.1) 82.5) 40 Packed Snow Surface 35 30 Stopping Distances (m) 25 20 15 10 5 0 Blizzaks Studded Tires All Season Icy Surface Figure 3.9) 85.7) 114.3 (39.3) Average 68.8) 91.5) 71.9 (27.7 (25.2 (27.9 (19.8 (29.5) 69.7) 76.2) 96. the Blizzaks and studded tires were more closely matched. averaged across each vehicle.1) 83.On the icy surface. Maximum deceleration for the three tire types. Table 9.2 (27.9 (27.3 km/h) Stopping Distances ft (m)) from Task 1 (based on Lu 1995) Snowy Surface Blizzaks Studded All Season Icy Surface Blizzaks Studded All Season Lumina 82.7 (24.2 (20.5) 90. Averaged 25 mph (40.
each vehicle was accelerated at maximum rate from a standstill and timed until it reached 20 mph (32.Starting traction performance tests were conducted similarly to those in 1994.58 Pickup 8. Table 10.35 9.71 The conclusions from these tests were that the Blizzaks offered the best overall traction performance on both packed snow and icy surfaces.86 9.9 Average 7.67 sec 7.07 Caprice 7.3 7. slightly ahead of studded tires.54 9.84 8. regardless of whether they were tested on snowy or icy surfaces. The studded tires appeared to lose proportionally more of their traction capability than did the other tires.14 7.65 sec 8.18 7.98 8.17 8.02 9. Averaged Starting Traction (Time to reach 20 mph (32.15 8.53 11.2 km/h).51 sec 8. Both these tire types performed considerably better than all season tires (11 percent better on snow and 25 percent better on ice).19 10.94 sec 8.18 11.68 7. The second task of the 1995 Alaska study (Lu 1995) compared the stopping traction performance of new “lightweight” studded tires (with aluminum studs) that have been developed in response to concerns about pavement damage from conventional steel studs. Braking tests were conducted in the same manner as previously—on both a packed 24 . but both the Blizzaks and the studded tires performed considerably better than the all-season tires.2 km/h)) (sec) from Task 1 (based on Lu 1995) Snowy Surface Blizzaks Studded All Season Icy Surface Blizzaks Studded All Season Lumina 7.95 8. Results (Table 10 and Figure 4) showed that nearly the same starting traction performance was obtained for the studded tires and the Blizzaks.
Starting Traction of Test Tires (Time to reach 20 mph (32. On an icy surface. the Blizzaks had the shortest stopping distance of the three tires tested. The tires with lightweight studs were new.3 km/h). Air temperature during these tests was about 0 degrees F (-18 degrees C). Two vehicles were used: the full-sized Chevrolet pickup and the Chevrolet Caprice. and about 16 percent behind the Blizzaks were the standard-studded tires. the standard studded tires and Blizzak tires were the same (used) tires that had been tested previously in this program and in the 1994 program. the 25 .snow surface and an icy surface.2 km/h (sec) 10 Icy Surface 8 6 4 2 0 Blizzaks Studded Tires All Season Figure 4. 12 Packed Snow Surface Time to Reach 32.2 km/h)) with All Vehicle Types Combined (sec) (Lu 1995) Stopping traction test results (Table 11 and Figure 5) showed that on a packed snow surface. About 10 percent behind the Blizzaks were the lightweight-studded tires. with the driver attempting locked-wheel stops from 25 mph (40.
2 (15.0) Average 55.5 (22.4 (16.6 (25.0 (25.8) 70.7 (24.4 (24. Table 11. Averaged 25 mph (40.3 (26.3 (12.3) 71.1 (23.3) 69.4) Caprice 40.2 (21. with braking distances approximately 11 percent shorter than the Blizzaks and about 17 percent shorter than the standard-studded tires.lightweight-studded tires showed the best stopping traction.2) 84.1) 83.5 (16.1) 61.3 (18.5 (21.7) 82.3) 79.6) 52.9) 65.3 (25.7) 76.3) 51.2) 86.1) 80.5) 30 25 Stopping Distance (m) 20 15 10 5 0 Packed Snow Surface Icy Surface Blizzaks Standard Studded Tires Lightweight Studded Figure 5.9 (21.3 km/h) Stopping Distances (ft (m)) from Task 2 (based on Lu 1995) Snowy Surface Blizzaks Standard Studded Lightweight Studded Icy Surface Blizzaks Standard Studded Lightweight Studded Pickup 72.9 (20. Stopping Distances (m) of Test Tires with All Vehicle Types Combined (Lu 1995) 26 .2 (21.6) 70.
instead of all four tires. On ice. the lightweight-studded tires had the greatest deceleration followed by the Blizzaks and standard-studded tires (the latter two of which were nearly equal). the greatest acceleration came from the standard studded tires. but the value was nearly identical to that of the Blizzaks. These tests were apparently conducted because the option of running two instead of four studded tires has been considered for reducing pavement wear. a front-wheel drive Chevrolet Lumina with ABS and a full-sized (rear-wheel drive) Chevrolet pickup truck. Tests were only for braking traction (not starting 27 . the 1995 Alaska research also examined the braking traction performance of two studded tires only. followed by the lightweight-studded and standard-studded tires. Comparisons were made for each vehicle equipped three different ways: standard studded tires on all four wheels.3 km/h).Stopping traction results measured with an accelerometer yielded results consistent with the stopping distance measurements: on snow. the Blizzaks had the greatest deceleration. On ice. But the greatest acceleration on snow came from the Blizzaks. the lightweight studded tires generally produced the best stopping and starting traction performance when compared with the Blizzaks and standard-studded tires. Starting traction performance produced similar results: the lightweight-studded tires on snow and ice required the shortest time to reach 25 mph (40. the Blizzaks and standard-studded tires were somewhat worn. Two vehicles were tested. In conclusion. In a third task. while the lightweight-studded tires were new. However. followed by the lightweight-studded tires. on just the front wheels (with all-season tires on the rear) and with all-season tires on all four wheels. as had been the case for all previous testing. mounted to the front wheels. which may have affected the results. followed by the Blizzaks.
4 km/h) initial speed was used. When test results from both snowy and icy surfaces were averaged (Table 12 and Figure 6). However. under certain conditions. the benefit to braking traction is roughly half of the benefit if studded tires are used on all four wheels. for rear-wheel drive vehicles such as the pickup truck. Presumably. particularly under braking and/or cornering.” while decelerating or cornering. starting traction performance would not be enhanced if studded tires were placed only on the front (non-driving axle). A more serious concern. This could cause the vehicle to become directionally unstable and to rotate about a vertical axis.traction) and were conducted similarly to those performed previously except that a 35 mph (56. the vehicle with two front studded tires performed about 8 percent better than the vehicle with four all-season tires. If the studded tires were placed only on the rear of the rear-wheel drive pickup. or “spin out. 28 . and about 7 percent worse than the vehicle with all four studded tires. It is possible that various vehicles. it is likely that the braking traction performance would not have been enhanced as much as with the studded tires in front (because of the forward weight distribution). Obviously. when tires of different friction factor were used in the front and rear. the use of two versus four studded tires would provide a commensurate decrease in pavement wear. could become unstable in yaw if mismatched tire types were mounted front to rear. This result confirms a fairly predictable outcome: when two studded tires are placed on the front wheels. however. further thought and testing must be applied to determine whether such a practice also may compromise other facets of vehicle performance. would be the directional stability.
1995) included an examination of the effects of tire wear and surface temperature on stopping and starting traction.7 (31.2) 99.9) Total Average 93.5 (34.6) Icy Surface Average 127. Averaged Stopping Distance (ft (m)) from Task 3 (based on Lu 1995) Tire Type Four Wheel Studded Standard Studded Lightweight Studded Snow Surface Average 92.3 (28.6 (31.3 km/h) and starting traction times to the same speed were measured on a packed snow surface at 29 .3) 34 33 Stopping Distances (m) 32 31 30 29 28 27 26 Four Wheel Studded Standard Studded Tires Lightweight Studded Figure 6.5 (28.5) 100.7) 109. Stopping distances from 25 mph (40.8) 101.2 (33.4 km/h) Stopping Distances (m) from Task 3 with All Vehicle Types and Surface Conditions Combined (Lu 1995) The fourth task of the Alaska study (Lu.5 (28.7 (30.0) 104. the same lightweight-studded tires tested while new in the second task were driven 1000 miles (1610 km) on the road.Table 12.4) 113.7 (30. 35 mph (56. For the tire wear tests.
3 km/hr) (40. Tests from the second task were run at temperatures of 0 degrees F (–18 degrees C).8) 6. Task 4 (based on Lu 1995) Studded Tire Type Stopping Traction Starting Traction New Lightweight Old Lightweight Difference 1 Stopping Distance (ft/m) Time (sec) to from 25 mph Reach 25 mph (40.3 km/h) 48.3 km/h) and about 2 percent longer to attain this speed than when they were new. whereas the tests for the fourth task were run at the freezing mark.2 (14.9 sec 12% 2% Caprice on packed snow surface. This confirmed that tire and stud wear diminish the traction performance capability of the tires. For these tests. stopping distance data at 25 mph (40. wherein new lightweight-studded tires were tested on the Caprice. 32°F.73 sec 55. A more formal test of the effect of temperature was performed as part of the fourth task.3 km/h) were collected for the full-sized Chevrolet pickup on packed snow and icy surfaces at temperatures 30 .about 32 degrees F (0 degrees C) both before and after the tires had been “worn” on the road.7) 6. Results (Table 13) showed that after accruing tire wear through use. the lightweight-studded tires required about 12 percent longer distances to stop from 25 mph (40. (0°C) Upon comparison with the second task.1 (16. Stopping distances were 6 percent longer at the colder temperature (for the “new” tires on a packed snow surface). the effect of temperature was noted. Stopping and Starting Traction Performance Comparison between New and Used (1000 mile/1610 km wear) Lightweight Studded Tires1. Table 13. Only the Chevrolet Caprice was used for this comparison.
1) 82.5) 82.1) 83.1 (23. Averaged 25 mph (40.0 (25.6) 82.2) 92. The only exception was the allseason tire on ice.5) 89. and all-season tires.2 (27.3 km/h) Stopping Distances (ft (m)) at Different Temperatures. the traction of the studded tires is particularly enhanced because of the more aggressive engagement in the ice by studs.9 (27. the studded tires showed the most significant difference—with 5 percent shorter average stopping distances at temperatures near freezing.5 (27. Thus.1) 80. Task 5 (based on Lu 1995) Snowy Surface Blizzaks Standard Studded All Season Icy Surface Blizzaks Standard Studded All Season Snowy-Icy Combined Blizzaks Standard Studded All Season Temp: -20°F (-29°C) 72.9 (26.7) Difference 0% 2% 12% 83.6) 77.3) 103.0) 90. Results generally showed that stopping distances were shorter at temperatures near freezing than at –20 degrees F (-29 degrees C).2) 88.7 (25.of -20 degrees F (-29 degrees C) and 32 degrees F (0 degrees C). One possible explanation for this is that at the higher temperatures.5) 2% 7% -6% 78. which stopped 6 percent shorter at the colder temperature.2) 96. the potential benefit from studs becomes less apparent as temperature drops.0 (25. the snow and ice are warmer and hence softer. Table 14.4 (23.8 (28.7 (24.3 (31.7 (23. With all vehicles and surface conditions combined and the results averaged (Table 14 and Figure 7).7 (25. Especially for ice near freezing.1) Temp: 32°F (0°C) 72.3 (25.5 (22. Blizzaks.5 (22. This differential was more than twice that of the all-season tires and five times that of the Blizzaks.8 (29.3) 77.6) 1% 5% 2% 31 . Three tire types were tested: standard studded tires.8) 85.
all-season tires. In these tests. They were stopped from 35 mph (56. Temperature Effects on 25 mph (40.3 km/h) Stopping Distances (m) of Chevy Truck (Lu 1995) The fifth task of the 1995 Alaska study examined vehicle lateral controllability during stopping maneuvers.3 km/h Stopping Distances (m) 29 28 27 26 25 24 23 22 21 Blizzaks Studded Tires All-Season -20 deg F 32 deg F Figure 7. four studded tires.4 km/h) on both snow and ice at temperatures near freezing. or two studded (front) and two all-season tires. and later analysis of the video tape allowed measurement of the maximum lateral displacement and maximum angular directional change. Results showed that for snow and ice combined. the all-season tires were next. A video camera recorded the vehicle trajectory. however.Averaged 40. the vehicle equipped with four studded tires had the best lateral traction performance (the least lateral displacement and least angular rotation). the test vehicles were fitted either with Blizzaks. 32 . and the other two groups followed. Results were very close. and the differences were not particularly significant.
3 (25.3 km/h). Stopping distances were measured for initial speeds of 25 mph (40.9) 82.9 (21.5) 69.2 (27.2 (15. the effect of vehicle type and drive configuration on traction performance was examined.3 (25.3) Studded All Season 87.8 (29.1) 50.1) 96.9 (27. tire size and contact area. and suspension dynamics.2 km/h) from a standstill.5 (22. A number of vehicle factors probably contributed to this difference.5) 90.7) 33 . as were times to reach 20 mph (32.For the sixth task in the 1995 Alaska study. In these tests. Drive configuration is not likely to have played a part in this disparity because the vehicles were being braked.1) 63.7 (25. Tests were conducted with standard studded tires.9 (19.2) 71.4) 84.2 (27. For starting traction tests. stopping and starting traction were compared for the front-wheel drive Chevrolet Lumina.7 (25.5) 89.8 (23.3 (18.9 (27. and rear-wheel drive Chevrolet Caprice.4) 89. particularly vehicle weight distribution.9) 81.5 (34.7) 83. Averaged 25 mph (40.7) 114. Results averaged across all conditions and tire types (Table 15 and Figure 8) showed that for the stopping traction tests.4 (24. half-ton Chevrolet pickup. The spread in results was not significant and was likely the result of experimental technique and the variation in vehicle parameters discussed above.1) 72.0 (31.8) 61.9) 103.7) 76.6 (31.6 (26.5) 104. and Blizzaks on snow and ice at very low temperatures of –20 to –30 degrees F (-29 to –35 degrees C).4) 128.3) Average 94.8 (28. ahead of the Lumina by 3 percent and the Caprice by 6 percent. rear-wheel drive. the truck had the best performance. ahead of the truck by 15 percent and the Lumina by 26 percent.2 (21.7) 90.2) 88.3 (39.9 (27. the Caprice stopped in the shortest distance. Table 15.3 km/h) Stopping Distances (ft (m)) from Task 6 (based on Lu 1995) Snowy Surface Lumina Chevrolet Pickup Caprice Icy Surface Lumina Chevrolet Pickup Caprice Blizzaks 82. allseason tires.
Studded tires may lose more of their tractive ability over time than Blizzaks. though performance differences for the studded tires and Blizzaks were not significantly different. 2.35 30 Stopping Distance (m) 25 20 15 10 5 0 Lumina Snowy Surface Icy Surface Chevrolet Pickup Vehicle Type Caprice Figure 8. though this conclusion may have been confounded by the fact that the lightweight studded tires were new. The non-studded Blizzak tires offered the best traction performance. while the other tires tested had been worn somewhat. The same was true for starting traction. while all-season tires showed the worst performance. 34 . especially for braking on both packed snow and ice. Stopping Distances (m) of Test Vehicles with All Tires Combined (Lu 1995) The following overall conclusions were drawn from the Alaska Studies (Lu 1995): 1. Tests showed that lightweight (aluminum) studs produced better stopping and starting traction results on snow and ice than standard studded tires and Blizzaks.
Studded tires produce their best traction on snow or ice near the freezing mark and lose proportionately more of their tractive ability at lower temperatures than do studless or all-season tires. where worn tires with lightweight studs had stopping distances on snow that were 12 percent longer than when new. 5. but not for starting traction. and were not likely related to the drive configuration (front-wheel drive. 6. such as yaw instability. Lateral traction performance differences between the various tire groups did not show significant variation. 7. Wear on lightweight-studded tires diminishes their stopping and starting traction performance capability. and suspension dynamics. The Caprice stopped 15 percent shorter than the pickup truck and 26 percent shorter than the Lumina. rear-wheel drive). These differences were primarily ascribed to vehicle differences such as weight distribution. Tests of stopping and starting traction performance for different vehicle types and configurations on snow and ice showed that significant differences occur for braking distances. 35 . This effect was most prominent for braking maneuvers. tire size and contact area. Stopping and starting traction performance on snow and ice generally diminishes at temperatures below about 20 degrees F (-7 degrees C).3. The use of only two studded tires (on only the front wheels) produced stopping traction results on snow and ice that were about halfway in between the results of four studded tires and four all-season tires. should be considered. other controllability penalties. 4. However.
1) 36 . 1995) Packed Snow Surface Blizzaks Studded All Season Icy Surface Blizzaks Studded All Season Bare Pavement Blizzaks Studded All Season Lumina 62. Stopping distances were recorded from initial vehicle speeds of 25 mph (40.5 (35.3 km/h) at a location in Fairbanks on packed snow. On ice.2) 118. and Bare Pavement.7) 128. Ice.6) 63. but the differences were deemed insignificant. conducted by the University of Alaska at Fairbanks. than the studded tires.6) 63.8 (15.9 (38.9 (25. tests were conducted to determine the performance of studded tires in comparison with all-season tires and Blizzak tires on packed snow.7 (5.0 (31.6) 64.2) 128.4 (36.9 (46.6 (32. and bare pavement.9) 68. respectively. Stopping Distances (ft (m)) for 25 mph (40.2) N/A N/A N/A 16. Table 16. ice.5) Average 64.5) 59.3 (19. 1995).3 (19.OTHER PERFORMANCE DATA FROM ALASKA In another study performed in Alaska (Lu et al.3 (19. Fairbanks (based on Lu et al. the Lumina had four-wheel ABS.3 (19.6) 126.9 (19.0) 17.4) 104.1) N/A N/A N/A 16.4 (5.9) 106. but for this series of tests.8 (35.7 (5. The first test.6 (19.4 (5. Most tests were conducted at near-freezing temperatures.6) 116.3 (32.1) 83.2) 68.2) 16.3 km/h) on Packed Snow. Results (Table 16 and Figure 9) showed that all three tire types produced the same results on packed snow. and were shortest for studded tires followed by the Blizzaks (8 percent longer) and all-season tires (15 percent longer).7) 122.6 (39.4 (24.9 (21.0 (37.6 (20.6 (39.2) 16.0 (5.0 (5.0) Caprice 50. On bare pavement.1) 57. stopping distances for the Blizzaks and all-season tires were 5 percent and 2 percent shorter. involved the use of the same three types of vehicles used in the 1995 tests (Lu 1995). and bare pavement.0) 64.4 (17.5) 117.4) 105. stopping distances were generally two or three times longer than on packed snow. ice.2) 152.5) Pickup 79.4 (18.0) 17.
On bare pavement. Results showed that on packed snow. stopping distances were determined for packed snow. the Blizzaks and studded tires were nearly equivalent and both were significantly better than the all-season tires (Table 17 and Figure 10). the all-season tires were not tested. The vehicles were the same. respectively. and bare pavement. 37 . On the icy surface. the studded tires had stopping distances 40 percent and 42 percent longer than the Blizzaks and all-season tires. 1995) In a similar test. 1995). Stopping Distances (m) for Various Tires on Slippery and Bare Pavement. except that a Ford Crown Victoria (rear-wheel drive with ABS) was exchanged for the Caprice. ice. Fairbanks (Lu et al.45 40 Stopping Distance (m) 35 30 25 20 15 10 5 0 Packed Snow Surface Icy Surface Surface Type Bare Pavement Blizzaks Studded All Season Figure 9. but the studded tires stopped 11 percent shorter than the Blizzaks. conducted by the University of Alaska at Anchorage (Lu et al.
Temperature, Deg F. Figure 11. The Effect of Temperature (F) on Traction for Studded and Non-studded Tires (Alaska Studded Tire Study, Phase III, 1973) percent longer when the concrete was wet. For four studded tires, this difference increased to 16 percent for dry conditions and 32 percent for wet conditions. Though such statistics may not be entirely valid for today’s CP studs, radial tires, and ABS, they still indicate a trend that is likely to be valid: studded tires on wet or dry concrete provide less traction than non-studded tires. This is likely because the studs cannot penetrate the harder roadway surface, which actually lowers the effective coefficient of friction, in much the same way as studded tires lose effectiveness on ice at lower temperatures.
The study found no significant difference in accident involvement 42 . Some of these driver behavioral factors will be discussed in a later section. they may have been purchased by “safer drivers” who were more concerned about safety and hence likely to have a lower accident rate. the difference in friction between studded tires and non-studded winter tires is likely to have become smaller over time. on the order of 1 to 10 percent. It was concluded that the use of studded tires improves road safety by reducing the accident rate. Accident rate declines for vehicles equipped with studded tires that were presented in the 1970s have been postulated to have been wrong because of “selective recruitment” of the drivers (Elvik 1998). Other confounding factors may have skewed historical and more recent accident rate predictions. A separate Norwegian study sent a questionnaire to drivers who reported car damage during the winter of 1994/1995 to assess the effect of studded tires on winter accident rates. Early data (from the 1970s) often suggested much greater reduction in accident rates for users of studded tires (on the order of 40 to 70 percent). which is not likely to be accurate anymore. the true safety benefits of studded tires have been reduced relative to non-studded tires. This disparity is caused by several factors. but the effect is quite small. First. studless winter tires. Also.The Norwegian study statistically analyzed the results of these 11 studies and classified them by strength. Hence. drivers using non-studded tires reportedly cancelled more trips and drove more cautiously than those with studded tires. The gap has narrowed both because regulations around the world have limited the aggressiveness of the studs and because tire technology has improved the frictional characteristics of newer. When studded tires were newly available. regardless of what tire they were using.
A 1993 ban of studded tires in Japan resulted in “extremely slippery” roads. which can cause complete lack of control. rutting allows standing water to accumulate in wheel troughs. smoother pavement. 2001). or by upsetting the lateral stability while the car changes lanes (from rut to rut).” which adversely affects the directional controllability of a car by “steering” the car toward the center of the rut.between drivers with studded and non-studded tires when controlling for other car and driver characteristics (Fosser 1995). as 43 . In the mid-1980s in Hokkaido. studded tire usage rates were close to 100 percent. thereby raising the potential for hydroplaning. a higher numbers of accidents. Standing water in ruts can also cause excessive road spray to obscure the vision of nearby motorists. DRIVING HAZARDS CAUSED BY PAVEMENT WEAR Several obvious and well-understood driving hazards result from pavement rutting caused by accelerated wear that is the result of studded tire use. either pavement or ice. During the period from 1989 to 1993. First. while studded tires tend to wear down this surface fairly quickly (Fridstrom 2001). When water is present. Non-studded tires tend to pack the snow into compact ice. INCIDENTAL TRACTION IMPROVEMENTS Some studies have suggested that the roughening of driving surfaces. Increased wear from studded tire use can also cause premature loss of pavement paint striping and marking. rutting can cause “tramlining. and a 20-fold increase in the amount of anti-freezing agents applied (Asano et al. by extensive use of studded tires may have an overall benefit to the traction (and hence safety) of the roadway.
The increase in risk was found not to be linearly dependent on the proportion of cars equipped with studded tires because even a small proportion of cars with studded tires is sufficient to roughen icy roads. the risk would increase by 17 percent. The study concluded that the overall accident risk in winter would increase by only 9 percent if only 50 percent of the vehicles were equipped with studded tires. Icy or snowy roads were postulated to have been moderately roughened through use of studded tires. If only 20 percent of the vehicles had studded tires. slippery roads did not become a problem until 1992 when the studded tire use rate fell below 20 percent. Another study concluded that a ban on studded tires resulted in a slight decrease in fatal and injury-only accidents but in an increase in skidding accidents (Minsk and Kajiya 1993). thereby improving traction for all vehicles whether or not they are equipped with studs.studded tires were phased out. A 1998 study in Sweden investigated diminished skid resistance on roadways caused by the advent of lighweight studs and wear-resistant pavement mixes (Hobeda 1998). According to a 1995 study. 95 percent of the vehicles in Finland are equipped with studded tires (Kallberg 1995). studded tire use in the winter months tended to roughen pavement texture and thus improve skid resistance in the summer. Hence. Before these developments. Another 44 . an unintended consequence of less pavement wear was lower skid resistance. Another Finnish study by the same author concluded that one of the positive aspects of studded tire use is that it provides better traction on pavements that are susceptible to wear by studded tires (Kallberg 1993). including those with non-studded tires that used the same roads. which made it safer for all vehicles.
It has been shown that even a small increase in speed can negate any increase in traction performance of studded tires. 45 .” wherein drivers of vehicles fitted with studded tires on fair days who encountered unexpected slippery conditions might have a traction advantage. hence increasing risk. though there is not consensus about the effects.Swedish study indicated that pavement roughening by studded tires improves wet friction traction on bare surfaces. Perhaps oddly. Yet another study concluded that drivers of vehicles with studded tires drive more safely than those with non-studded tires (Sigthorsson 1998). Some studies have shown that drivers using studded tires tend to be more confident and therefore tend to drive faster than those using non-studded tires (Fridstrom 2001. They postulated that this was because of a “surprise factor. their analysis also found that accident risk was reduced on days when there was no snow on the ground or in the air. 1995). Another study found the risk for drivers of vehicles with studded and non-studded tires to be equal (Fosser 1996). Kallberg et al. One body of research on the use of studded tires in Norway concluded that a reduction in the use of studded tires would not lead to a significant increase in injury accidents. creating a greater likelihood of control loss (Fridstrom 2001). thereby improving grip for vehicles both with and without studded tires (Oberg 1994). The researchers found that during severe winter conditions. drivers of vehicles with studded tires tended to drive faster than others. and that such drivers had not lost this advantage by adapting (upward) their speed relative to drivers of vehicles without studded tires. DRIVER BEHAVIOR Human behavior should not be overlooked in assessing the safety of studded tires.
However. Drivers who had previously been using studded tires did not want to switch back to using studded tires (Roine. 46 .000 miles. cannot be driven on the street in the summer months. The researchers found that drivers using studless tires braked more softly. 1994). its studs can be removed. in Washington. negotiated steep curves more carefully.000 to 40. and it can be used as a highway tire. including the trade-off in the use of traditional snow-clearing methods the introduction of suspended particulate matter (dust) from roadway wear increased noise from studded tires. the Blizzak can easily (and legally) be “used up” during non-winter months. a typical 205/60-14 studded snow tire costs approximately $60 (equipped with studs). Cost of Studded versus Studless Tires An informal survey of tire costs in the Seattle area revealed that typical winter tires for a mid-sized car vary substantially in cost.A study from Finland also examined driver behavior. The studded snow tire. drove at lower speeds. and expressed complete satisfaction with the studless tires. OTHER FACTORS AFFECTING THE USE OF STUDDED TIRES Other factors to be considered in the debate over the use of studded tires include such issues as the cost of studded tires in comparison with new studless winter tires the increase in fuel consumption for studded versus studless tires convenience and mobility. After its useful life as a snow tire. The same size Blizzak tire costs closer to $100. Each tire is designed to give three or four average winter seasons before losing effectiveness as a winter tire. For example. the Blizzak is designed to operate at its best for 30.
3) increased fuel consumption by 0. on the average. than that of studless tires. The tangible and intangible costs and benefits of studded tires and other traction-enhancing options must be compared with alternative methods of gaining mobility. which showed that studless tires.Fuel Consumption Field measurements conducted in Finland showed that slippery. Given data presented from the Alaska studies (Lu 1994. and road surface unevenness far outweigh the effects of studs on tires.4 to 0. ice. Fuel consumption with studded tires was about 1. for most circumstances. dry. and uneven roadway surfaces can increase fuel consumption by 15 percent over bare. 47 . For some states. and even surfaces (Anila 1994). relative effects on fuel consumption of snow. Convenience and Mobility There is an intangible value of the mobility gained from the opportunity to use vehicles on roadways regardless of the weather.1 (from 0. snowy.7 percent. fuel consumption for studded tireswill likely be higher. A decrease in coefficient of friction of 0. The difference in fuel consumption between bare pavement and the most slippery icy road was 4 percent. The use of studded tires affords users (at least) the perception of convenient icy-weather traction without the inconvenience associated with either staying home or using temporary traction aids such as chains. have better traction than studded tires. including winter highway snow and ice control.2 percent higher than that with studless winter tires. Hence. winter highway maintenance comprises a large part of the yearly budget. However. 1995). which is a function of the roadway condition. the fuel consumption of studded versus studless tires depends on which tire creates the best traction.
Tests from the early 1970s showed that the increase in noise from studded tires (as compared with non-studded tires) was most prominent at speeds of 20 mph (32 48 . Mechanical interaction between the stud and pavement releases particulate matter (airborne dust) that is considered a risk to human health. Suspended Particulate Matter While pavement damage and subsequent increases in hydroplaning and road spray have been well documented. By the winter of 1998-1999. the increase in suspended particulate matter (SPM) or dust from stud use is a more complicated safety issue. can be roughened by the use of studs). NCHRP 1975). pavement roughness can transmit vibration to the vehicle chassis.In Hokkaido. Noise levels for pavement-tire contact are also affected by the roughness of the pavement surface (which. In fact. 2001). Noise Further studies have documented the increase in noise from vehicles equipped with studded tires (Fridstrom 2001. concerns about air pollution from airborne dust resulted in a national ban on studded tires in Japan in the early 1990s. In addition to increased ambient noise levels from these effects. the roadway maintenance costs increased sharply throughout the 1990s. where studded tire use was banned in 1990. in turn. Several studies performed in Japan documented the significantly increased presence of this dust during periods of stud usage (Fukuzaki 1985 and Asano 2001). causing passenger discomfort and an increased rate of vehicle deterioration. Japan. the use of deicing agents had increased by 20 times and abrasives had increased 30 times the amount applied in 1991-1992 (Asano et al.
at higher speeds of 60 mph (96 km/h). the differences diminished somewhat (NCHRP 1975). For noise increases on roughened pavement compared with adjacent (smoother) pavement. 49 . the differences were most pronounced when measured inside the vehicle.km/h).
acceleration. cornering. and with the advent of the new “studless” tire. the relative frictional gain of studded tires diminishes or becomes negative on roughened ice. where they have been shown to provide up to 100 percent gain in certain tests. a condition whose occurrence is limited. studded tires performed as well as or worse than the Blizzak tire. With less aggressive (lightweight) studs being mandated. Traction performance can be characterized in many ways. controllability. the increment usually was small. 4. The precise environmental conditions under which studded tires provide a traction benefit are relatively rare. Studded tires produce their best traction on snow or ice near the freezing mark and lose proportionately more of their tractive ability at lower temperatures than do studless or all-season tires. or if the comparison is made with studless tires. The traction of studded tires is slightly superior to studless tires only under an ever-narrowing set of circumstances. and for ice at lower temperatures. since the early 1990s. For those conditions in which studded tires provided better traction than studless tires. and grade climbing. Though all factors 50 . However. For the majority of test results reviewed for snow. 3. 2.CONCLUSIONS 1. including braking. as the studs wear. the traction benefit for studded tires is primarily evident on clear ice near the freezing mark. The maximum frictional gain (in comparison to non-studded (not studless) tires) is found for new studded tires on smooth ice. as the temperature drops. such as the Blizzak.
in comparison to non-studded tires. 5. there is little difference in stopping distance between studded and non-studded tires. 7. other controllability penalties. However. studded. studless Blizzak tires offered the best traction performance. which in turn were 8 percent shorter than for all-season tires. studless.are important. 51 . Studded tires reduce the difference in friction factor between optimum-slip and locked-wheel braking. studded tires tend to have poorer traction performance than other tire types. the single best indicator of tire performance is braking distance and deceleration. In another set of tests in Alaska. in comparison to studded tires (which were second) and all-season tires (which were last). This may reduce the risk of drivers misjudging the necessary braking distance and may improve the braking potential for anti-lock brakes. should be considered. In one set of stopping distance tests in Alaska. when averaged across several vehicles. for asphalt. such as yaw instability. 6. especially for braking on both packed snow and ice. stopping distances for studded tires were 15 percent shorter than for Blizzaks. This is especially true for concrete. On bare pavement. On ice. The use of two studded tires on the front of a vehicle produced stopping traction results on snow and ice that were about halfway between the result of four studded tires and four all-season tires. and allseason tires performed nearly equally on snow. 9. 8.
and premature damage to pavement markings. Studded tires may lose more of their tractive ability over time (from stud wear) than studless tires. A number of driver behavior issues have been postulated to affect the judgment of studded tire effectiveness.043 in. 16. glare ice. 52 . Tire tread wear (on studded tires) has relatively little frictional effect if stud protrusion is maintained at 0.1 mm). There is not consensus on these points: 1) drivers with studded tires care more about safety. The cost of studless tires is significantly higher than studded tires—by approximately 50 percent. Tractive performance of studded tires is sensitive to stud wear.039 to 0. hydroplaning on accumulated water in the ruts. Studded tires increase fuel consumption by a small amount (~1. 2) they drive faster (because of a false sense of security or confidence). 15.6 mm). 13. When stud protrusion diminishes to 0. hence they drive more safely. A Norwegian study concluded that the use of studded tires tends to reduce the accident rate by a small amount—from 1 to 10 percent.0-1. 12. The roughening of ice and pavement from studded tires provides a safety benefit for all vehicles (with and without studs) by helping to prevent formation of smooth. (1.024 in. 11. 14. and 3) drivers with non-studded tires avoid driving when weather is severe.10. the frictional effect from the studs becomes negligible. excessive road spray. Pavement rutting caused by accelerated wear from studded tires can cause the dangerous conditions of tramlining. (0.2 percent) over non-studded tires on bare roadways. But the other effects of unevenness.
Suspended particulate matter from pavement dust created by studded tires and noise from studded tires are health concerns in heavily traveled urban areas.snow. 17. 53 . and ice are far more significant than this factor and can increased fuel consumption by 15 percent.
Kopac. T.” Transportation Research Record 1741. J. 1. May 11-13. Thesis. Fosser.” Nordic Road and Transport Research No.. “The Use and Effects of Studded Tires on Oregon Pavements.. Brunette.. Norio. Motoki. Hobeda. “A Synthesis On Studded Tires. Yanaka. Fosser. Vol. Oregon State University. and A. Anila. “The Effects of Icy and Snowy Road Surface Conditions on Fuel Consumption. Lasse. 1998.” Accident Analysis and Prevention 31. Asano. Budapest. Rune.S. Fridstrom. Mahoney.REFERENCES “Alaska Studded Tire Study Phase III. 54 .” State of Alaska. “The Effects on Accidents of Studded Tires and Laws Banning Their Use: A Meta-Analysis of Evaluation Studies. “Recent Situation of Winter Road Management and Traffic Accidents in Hokkaido. 2001.” Washington State Department of Transportation. Olympia. “Studded or Non-Studded Tires: No Significant Difference in Risk of Accidents. 1981. “The Interaction between Wear and Polish on Swedish Roads. 2. Stein. Hungary. M. Peet. Elvik. 1986. G. No. Kallberg.” Atmospheric Environment. F. Wash. 20. A. and P.” Institute of Transport Economics 310/1995. “Evaluation of Winter Driving Traction Aids: Final Report. Hayhoe. Stein.” First World Conference on Highway Surfacing. and Y. Pennsylvania. Moore.” Finnish National Road Administration. O’Brien. and S.” M. “The Safety Effect of Studded Tyres in Norwegian Cities. 2001. December 1973. Washington D.C.” Institute of Transport Economics. Matti. V. University Park.1994. Nordic Road and Transport No.” Pennsylvania Transportation Institute. Oikawa. Urushiyama. “Effects of Studded Tires On Roadside Airborne Dust Pollution in Niigata. Fukuzaki. 1995. Michael J. 1. Corvallis. Japan. R. Hirasawa. 1995.E. 1999. 1996.. Angerinos. 1999. B. Department of Highways.. and Torbjorn Jacobson.-P. “Winter Tires With and Without Studs.
National Research Council..” Swedish Road and Traffic Institute. “Studded Tire Performance and Safety. Veli-Pekka. Nordic Road and Transport Research. 1994. J. 2. Washington. Jian J. Roine. 1994. Mazen G. No. D. Washington State Department of Transportation.wa. ISSN 07883722. Samuelsson. University of Alaska. Oberg. TRB. Kajiya. 1994.” http://www. and E. “Estimation of Effects of Reduced Salting and Decreased Use of Studded Tires on Road Accidents in Winter. 1993.C. Fairbanks.” Transportation Research Center. Esch. National Research Council. 1995. Helsinki.C. “Winter Vehicle Traction Controllability Performance. Kanner. Washington D. Washington... “Reduced De-icing on Rural Roads in Finland—Effects in Winter 1992-1993.” Proceedings of the ASCE 3rd International Conference on Applications of Advanced Technologies in Transportation Engineering..” Transportation Research Center. “Studded Winter Tyres and Traffic Safety.. Jian. 3. Seattle. University of Alaska.wsdot. Veli-Pekka..” Finnra 86/1993. 1993. Salem. Olle. October 1820. Fairbanks Alaska. Jian J. Nordstrom. Oregon. “Driver Behaviour on Sharp Curves and Queues on Main Roads.” Transportation Research Board. 1995. No. TIEL 3200210. 2000.. Vol. Lu.” Proceedings. Kallberg. D.C. Gudrun. 1998. Helsinki. “ FinnRA Reports 87/1993. 1975. 10. 1995. Sweden. Sigthorsson. M. Roine.” Oregon Department of Transportation. Minsk.” Transportation Research Record 1533.” Transportation Research Record 1501. and M. “Low Cost Winter Maintenance-Swedish Experiences. “Road Grip of Winter Tyres. ISBN 051-47-8786-4. “Snow and Ice Control in Japan and United States. of the OECD Workshop on Road Winter Maintenance. “Effects of Studded Tires. Lu. D. Malik. National Cooperative Highway Research Program. TRB..Kallberg.gov/traveler/wintertravel/studtire. Haraldur. Praha. T. 1991. L. and Y. and D. David. Alaska. Lu. “Winter Driving – Studded Tires. Junge. “Studded Tires In Oregon. H. “Evaluation of Winter Vehicle Traction with Different Types of Tires.htm 55 .” Nordic Road and Transport Research. Makinen. Finland. Finnish National Road Administration. Wash..
Hayhoe. A. B. 1995. December 1973. No. “Winter Tires With and Without Studs. T. 1. Tanabe. 20. Greek. Urushiyama.BIBLIOGRAPHY “Alaska Studded Tire Study Phase III. Stein. Earnest R.” State of Alaska. Angerinos. Kallberg. Wash. Norio..” Institute of Transport Economics.E. Oregon. and P. Corvallis.” State of Alaska. Michael J...” Pennsylvania Transportation Institute. 2. Fridstrom. Nordic Road and Transport No.1. 1999. and S.” Atmospheric Environment. Brunette.1994. “Alaska Garnet Tire Study. 1996.” M. Stein. J. Moore. “The Use and Effects of Studded Tires on Oregon Pavements. and S. Mahoney. Rune. Fukuzaki. “Economic Evaluation of Banning Studded Tires Due to Environmental Impacts.” Transportation Research Record 1741. 2001. “Recent Situation of Winter Road Management and Traffic Accidents in Hokkaido. Asano.” Nordic Road and Transport Research No. Lasse. F..S. and Y. Hara. Kopac. 2001. Oregon State University. Department of Highways.. University Park. Department of Highways. Fosser. 56 . Asano.” Institute of Transport Economics 310/1995.” Transportation Research Board. 1975. G..-P. O’Brien. Matti. 1986. Japan. Washington D. “The Effects of Icy and Snowy Road Surface Conditions on Fuel Consumption.” Finnish National Road Administration. Vol. Thesis.” Accident Analysis and Prevention 31.. M. and A. “Studded or Non-Studded Tires: No Significant Difference in Risk of Accidents. 2002. Anila. S. “Evaluation of Winter Driving Traction Aids: Final Report. “A Synthesis On Studded Tires. Olympia. F. Yokoyama. M. Fosser. 1995. 1981. Yanaka. “The Effects on Accidents of Studded Tires and Laws Banning Their Use: A Meta-Analysis of Evaluation Studies. “The Safety Effect of Studded Tyres in Norwegian Cities. R. Motoki.C. Washington D.. Oikawa. 1999. Pennsylvania. Hirasawa. “Effects of Studded Tires On Roadside Airborne Dust Pollution in Niigata. Elvik.” Washington State Department of Transportation. V.C.
2000.C.C. Jian J. Washington D. 1996. Malik. 1995.. 1995. “Winter Vehicle Traction Controllability Performance. “Studless Tires and Their Performance to Secure Safe Driving in Winter. T. 1995. Leppanen. 1995.” Finnra 86/1993. TRB. Hungary. Lu. Jian J. and D. Fairbanks. 24. Jian. Fairbanks. TRB. Washington. “Reduced De-icing on Rural Roads in Finland—Effects in Winter 1992-1993. “The Interaction between Wear and Polish on Swedish Roads. “Studded Tire Performance and Safety. Horiuchi.” Transportation Research Center.” In Transportation Research Record 1533. 1992. “Final Results of Road Traffic in Winter Project: Socioeconomic Effects of Winter Maintenance and Studded Tires. Jian J. 57 .” Oregon Department of Transportation. Salem. H. Mazen G. Jian J. and D.” First World Conference on Highway Surfacing. University of Alaska. Oct 28-Nov 1. and M.. 8th International Conference on Cold Regions Engineering. Eric. D. “Estimating the Traffic Safety Effect Of Studded Tires. 1996. Lu. Budapest. Ola. and Torbjorn Jacobson. Finland and Sweden.Hobeda.. National Research Council.. ISBN 051-47-8786-4.” Proceedings of the 6th International Pacific Conference on Automotive Engineering. Esch. Washington D.. Kallberg. Fairbanks.” Accident Analysis and Prevention. Sterley. T. Johnson.” Transportation Research Center. Roine. 1995. Lu. Fairbanks Alaska. University of Alaska. Peet. Anne. 1993. Kanner.. TRB. “Evaluation of Winter Vehicle Traction with Different Types of Tires. Alaska.. National Research Council.” Transportation Research Record 1533. “Estimation of Effects of Reduced Salting and Decreased Use of Studded Tires on Road Accidents in Winter. South Korea.” Transportation Research Record 1536. Veli-Pekka.. Seoul. “Vehicle Traction Performance on Snowy and Icy Surfaces. Alaska. National Research Council. Vol. Junge. TRB. D. “Studded Tire Research in Norway. Kazu. Veli-Pekka. Junghard. No. Lu. Barter.” Transportation Research Record 1501. J. 1991..” Proceedings of the 1996 8th International Conference on Cold Regions Engineering... May 11-13. Helsinki. Lu.C. Kallberg. Makinen. ISSN 07883722. “Studded Tires In Oregon. “Vehicle Traction Performance Comparison for Alaska Winter Seasons. Washington D.” Proc. 1998. 1994. Alaska. Oregon.C. 4. TIEL 3200210.
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§ 204-24-030. (4) When a tire is sold or offered for sale as a studded tire or when studs are installed in a new tire or a newly-recapped tire. Standards for Studded Tires: Studded tires shall meet the following specifications: (1) Studs shall be metal. Order 6902. § 204-24-030.] A-1 . School buses and fire department equipment tires are exempt from subsection (6) of this section. [Statutory Authority: RCW 46. Order 7607. 00-15-009. (3) Metal studs may be installed only by the tire manufacturer. (5) A tire shall contain a minimum of fifty-six metal studs at all times in order to qualify as a "studded tire" or as an approved traction device where traffic control signs marked "approved traction tires required" are posted. § 204-24-030. 83-21080 (Order 83-10-01). (2) Metal studs shall be inserted only in a new tire or a newly-recapped tire which has molded in the tread the "pin-holes" into which metal studs are to be inserted. (6) (7) Metal studs shall not be installed in any tire of a vehicle which has a gross vehicle weight of ten thousand pounds or over.APPENDIX A State of Washington Laws Regarding Studded Tires WAC 204-24-030. or by a tire dealer or tire jobber who shall install the metal studs in conformance with the manufacturer's specifications. tipped with tungsten carbide.330. there shall be a minimum of seventy metal studs evenly spaced around the tread of the tire.37. 92-05-016. effective 3/12/92. filed 10/19/83.12. Studs shall not be inserted in any new tire or newly-recapped tire after it has been driven on a vehicle. filed 9/14/76.420. § 204-24-030. effective 8/10/00. § 204-24-030. filed 2/10/92. Statutory Authority: RCW 46. filed 2/17/70. filed 7/10/00.
As used in this title. [1999 c 219 § 1.272.3 grams if the stud conforms to TSMI stud size 15 or 16.] Proposed State of Washington Laws Proposal is currently still being debated at the committee level (Staff: Jennifer Ziegler 786-7316).0 grams if the stud conforms to TSMI stud size 17 or larger. this means a stud that is recommended by the manufacturer of the tire for the type and size of the tire and that: (1) Weighs no more than 1. A lightweight stud may contain any materials necessary to achieve the lighter weight. ensure that current and future money is spent wisely. (2) Weighs no more than 2. regional.RCW 46. or (3) Weighs no more than 3. and prepare a 20-year plan for funding and A-2 . SENATE BILL REPORT SB 5747 SENATE COMMITTEE ON TRANSPORTATION Background: The Legislature and the Governor formed the Blue Ribbon Commission on Transportation in 1998 to assess the local. Lightweight Stud: "Lightweight stud" means a stud intended for installation and use in a vehicle tire.5 grams if the stud conforms to Tire Stud Manufacturing Institute (TSMI) stud size 14 or less. make the system more accountable and predictable.04. and state transportation system.
rail. Effective Date: The bill contains an emergency clause and takes effect on July 1. 2001. shipping. retailers may only install lightweight studs on tires. The commission consisted of 46 members representing business. Summary of Bill: Beginning July 1. ports. and the general public. The buyer of the tires must pay the fee to the seller of the tires and the seller must send the fees to the Department of Revenue. preservation. trucking. In 1999. and improvement of the entire transportation system so that transportation benchmarks can be achieved. agriculture. The Washington State Department of Transportation projects that by July 2005. Appropriation: None. tribes. labor.investing in the transportation system. the Legislature enacted a bill requiring wholesalers to only sell lightweight studs for tires. 2001. Recommendation Five outlined several ways to invest in maintenance. environmental interests. The fees must be deposited in the motor vehicle fund. lightweight studs will be the only studs on the road. 2001 (bill has not yet passed). Starting July 1. The commission made eighteen recommendations to the Governor and the Legislature. The commission concluded that one method for preserving the transportation system was to phase out studded tires or establish a surcharge to recognize the cost of studded tire damage to the roadways. 2001. A-3 . Fiscal Note: Requested on February 1. transit. a fee of $15 per tire is levied on the sale of each studded tire. government.
2002 REGULAR SESSION -Jan 14 By resolution. reintroduced and retained in present status. A-4 . -. Representatives Fisher. reintroduced and retained in present status.WASHINGTON STATE LEGISLATURE History of HB 1670 HB 1670 Sponsors: By Request: Imposing a fee on studded tires.2001 1ST SPECIAL SESSION Apr 25 By resolution.-. referred to Transportation.2001 REGULAR SESSION -Jan 31 First reading. Mitchell. Ruderman. Poulsen The Blue Ribbon Commission on Transportation Companion Bill(s): SB 5747 -.
automobiles with out-of-state registrations (only if automobile is in the course of passing through the state for a period of not more than 30 days). Studs which do not damage highway are permitted. Not permitted except for snow and ice driving conditions Not permitted. Permitted: Sept. Exception: school buses may use studded tires any time during the year. Also school buses from November 15-April 1. vehicles used to deliver mail. Permitted: November 1-April 15 Permitted: November 15-April 1 Permitted if not projected more than 1/16-inch when compressed. Permitted: October 1-April 15 Not permitted. Permitted: October 1-May 1 Permitted: November 1-April 1 Permitted: November 1-April 15 Permitted: No restrictions. Check local officials. Rural mail carriers may use studded tires under certain conditions. Metal illegal. Sept. 15 — May 1 north of 60 degrees N. SOURCE: AMERICAN AUTOMOBILE ASSOCIATION B-1 . Not permitted. School buses and municipal fire vehicles permitted to use studs anytime. Permitted: No restrictions. Not permitted except under certain conditions. Chains required in snow emergencies.APPENDIX B Other Studded Tire Regulations STATE STUDDED TIRE REGULATIONS Alabama Alaska Arizona Arkansas California Colorado Connecticut Delaware District of Columbia Florida Georgia Hawaii Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New Hampshire New Jersey New Mexico New York North Carolina North Dakota Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont Virginia Washington West Virginia Wisconsin Wyoming Rubber studs permitted. Permitted: October 1-May 1 Permitted: November 15-April 15 Permitted: November 1-April 30 Permitted: Year Round Permitted: November 15-April 30 inclusive Permitted: October 15-April 15 Permitted: October 15-April 15 Not Permitted. Full time nonresident students and nonresidents employed within Minnesota are not permitted use of studded tires regardless of vehicle registry. Permitted: October 1-April 15 Not permitted. Permitted: October 16-April 30 Permitted: No restrictions Permitted: October 15-April 15. Permitted: October 15-March 31 Permitted: No restrictions Permitted: October 15-April 15 Permitted: November 1-April 1 Permitted: November 1-April 15 Not permitted except for authorized emergency vehicles. Permitted: October 1-May 1 Not permitted except in western counties: Nov. Permitted: November 1-April 15 Permitted: November 1-April 1 Permitted: November 1-April 1 unless specified differently by Department of Transportation because of weather conditions. Permitted: November 1-March 31 Permitted: October 1-May 31 Permitted: November 1-April 1 Permitted: October 1-April 30 Permitted: No restrictions Permitted: November 15-April 1 No regulations. Permitted: October 1-April 30. 1-March 31 Permitted: November 2-April 30 unless otherwise authorized by registrar. Only studs that will not damage the highway are permissible. Not permitted except for nonresidents who are subject to certain restrictions. Not permitted. 30-April 15 south of 60 degrees N.
Figure B-1. school buses from Nov. Texas—Studs that will not damage the highway are permissible. Minnesota—Exceptions: nonresidents.Exceptions Florida—Studs that do not damage the highway are permitted Georgia—Exception: snow and ice driving conditions. rural mail carriers under certain conditions. who are subject to certain restrictions. Maryland—Exception: western counties Nov. 15-April 1. vehicles with out-of-state registrations. vehicles used to deliver mail. States in Which Studded Tire Use Is Not Permitted INTERNATIONAL REGULATIONS ON USE OF STUDDED TIRES (LU 1994) Canada Ontario Quebec Nova Scotia Newfoundland New Brunswick Prince Edward Island British Columbia Manitoba Saskatchewan Germany Sweden Finland Japan Prohibited Permitted October 15-April 15 Permitted October 15-April 15 Permitted November 1-April 30 Permitted October 16-April 14 Permitted October 1-May 31 Permitted October 1-April 30 Permitted October 1-April 30 No Restriction Prohibited October 31-Easter November 1-March 31 Prohibited B-2 . 1-March 31 Michigan—Exception: certain conditions. Wisconsin—Exceptions: authorized emergency vehicles.

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