ACKNOWLEDGMENTS

This guide was prepared by the Law En- forcement Standards Laboratory (LESL)

of the National Bureau of Standards under the direction of Jared J. Collard, Acting Manager, Selected Systems

Program, and Jacob J. Diamond, Chief

of LESL. The cooperation of the

following organizations is gratefully acknowledged: the International Association of Chiefs of Police, the Safety Research Laboratory of the National Highway Traffic Safety Administration, the Automotive Division of the General

Services Administration, the Tire Industry Safety Council, the North American Testing Company and the many tire manufacturers. The preparation of this guide was sponsored by the

National Institute of Law Enforcement and Criminal Justice, Lester D. Shubin, Standards Program Manager.
AUG 3 }^79

GUIDE TO

HIGH SPEED PATROL CAR TIRES

NBS Special Publication 480-33

by

Alvin C. Lewis

Ernest Lewis, Jr. Center for Consumer Product Technology

and the

Law Enforcement Standards Laboratory

Center for Consumer Product Technology

National Bureau of Standards

Washington, D.C. 20234

prepared for National Institute of Law Enforcement

and Criminal Justice

Law Enforcement Assistance Administration

U.S. Department of Justice

Washington, D.C. 20531

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
Library of Congress Cataloging in Publication Data

Lewis, Alvin C. Guide to high speed patrol car tires. (NBS special publication ; 480-33)

1. Tires, Rubber—Handbooks, manuals, etc. 2. Police vehicles- Tires— Handbooks, manuals, etc. I. Lewis, Ernest, joint author. H. Law Enforcement Standards Laboratory. III. National Institute of Law Enforcement and Criminal Justice. IV. Title. V. Series: United

States. National Bureau of Standards. Special publication ; 480-33. QC100.U57 no. 480-33 [TSI912] 602Ms [629.2'48] 78-10698

National Bureau of Standards

Special Publication 480-33

Nat. Bur. Stand. (U.S.), Spec. Publ. 480-33, 42 pages CODEN: XNBSAV

U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1979

For sale by the Superintendent of Documents

U.S. Government Printing Office. Washington, D.C. 20402

(Order by SD Catalog No. CIS. 10:480-33) Stock No. 003-003-02073-7

Price $2.00

(Add 25 percent additional for other than U.S. mailing).
CONTENTS

Foreword v Introduction l Application Aspects 2 Types of Roads Driven 2 Pursuit Driving 3

Tire Maintenance 3

Hazard Exposure 4

Types of Tires Used 4

Tire Mileage 4

Snow Tires 4

Radials Versus Snow Tires 5 Technical Aspects 6

Construction 6

Bias-Ply 6

Bias-Belted 6

Radial 6

Tire Markings 7 Tire Materials 9

Use of Chains 9

Tires and Gasoline Mileage 9

Selection and Purchasing of Tires .... 10

Principles of Selection 10

Cost Factors 10

Performance 10

Braking Traction 11 Cornering Traction 14 Driving Traction 14 Endurance and Tread Wear ... 14 Operational Aspects 15

Installation 15

Mounting Tires on Wheels .... 15

Inflation Pressure 17 Radial Run-Out 18

Balancing 19

Alignnnent 23

Safety Precautions 23

Operations 24

Break-in 24

Inflation and Loading 24

Road Conditions 24

Driver Habits 24

Mechanical Condition of Vehicle . . 25

Maintenance 25

Inflation Checks 25

Tire Rotation 26

Detection of Faults and Impending

Troubles 26

Mixing and Matching Tires 26

Positioning of Least Worn Tires . . 27

Abnormal Tread Wear 27

Repairs and Servicing 27

lACP Postscript 28

References 29

Appendix A 31 Appendix B 32

Appendix C 37

iii
LIST OF TABLES

1 . Distribution of police departments that use and do not use high speed pursuit

tires, by geographic area (1975) 2

2. Distances at which police departments abort high speed pursuits (1 975) 3

3. Major tire problems of police departments, by geographic area (1975) 4

4. Average tread life for each type of tire, by geographic area (1 975) 5

5. Tire failures, by construction 1

6. Description of police tires, in order tested 12

7. Ranking of 10 pairs of police tires for braking, cornering, driving and spinning traction 13

iv
FOREWORD

The Law Enforcement Standards Laboratory (LESL) of the National Bureau of Standards (NBS)

furnishes technical support to the National Institute of Law Enforcement and Criminal Justice

(NILECJ) program to strengthen law enforcement and criminal justice in the United States. LESL's function is to conduct research that will assist law enforcement and criminal justice

agencies in the selection and procurement of quality equipment.

LESL is: (1) Subjecting existing equipment to laboratory testing and evaluation and (2) conducting research leading to the development of several series of documents, including

national voluntary equipment standards, user guides, and technical reports.

This document is a law enforcement equipment guide developed by LESL under the sponsorship of NILECJ. Additional guides as well as other documents are being issued under the LESL

program in the areas of protective equipment, communications equipment, security systems,

weapons, emergency equipment, investigative aids, vehicles and clothing.

Technical comments and suggestions concerning this guide are invited from all interested

parties. They may be addressed to the authors or to the Law Enforcement Standards Laboratory, National Bureau of Standards, Washington, D.C. 20234.

Jacob J. Diamond

Chief, Law Enforcement Standards Laboratory

V

INTRODUCTION

Tires form one of the major subsystems of an

automobile. They serve as the interface

between the road and the car's brake, suspension and steering systems; they provide the

traction that starts and stops the vehicle; they

absorb a portion of the initial impact with a road

defect; and they provide the traction necessary

for steering. Tires also contribute to the comfort

characteristics of the ride and affect the perfor- mance obtained from the engine. Pursuit tires,

i.e., those certified for speeds up to 125 mph

(200 km/h),^ have the additional task of performing these functions at high speeds.

Tire purchases comprise a significant portion of a police department's transportation budget.^ If they are not properly selected and cared for, they wear faster, reduce gasoline mileage,

make the car handle poorly on the road, and

may cause accidents. Properly selected and

maintained tires can save money and improve

the safety and performance of patrol cars.

Selecting the best type of tire for use by a partic- ular department is not an easy task because of the various conditions under which they are used. The selection of pursuit tires on the basis

of their wet traction capabilities has been particularly difficult, due to the lack of comparative in- formation on different brands, constructions,

and sizes. One thing definitely known is that

non-pursuit tires are not advisable for high

speed police work! [3]^

This guide is designed to supply the information

needed to select tires to suit particular needs

and to maintain them for maximum safety, tire

life, and performance.

^ This guide gives data in the familiar English units followed,

in parentheses, by their approximate metric equivalents, rounded to the nearest meaningful unit. Measurements or

units quoted from other sources may not have metric

equivalents.

^ Based on information obtained from a 1 976 survey by the

International Association of Chiefs of Police, 379 police

departments spent nearly $5,400,000 for pursuit tires in 1975, an average expenditure of more than $14,000 per department.

^ Numbers in brackets refer to the references listed on page

29.
APPLICATION ASPECTS

Police patrol vehicles are subject to far greater

strain and punishment than regular passenger

cars. The same holds true for the tires. Given

this, one might assume that most patrol

vehicles would be equipped with high performance tires that are designed for high speed

traction and durability. However, a survey of police departments throughout the country by

the International Association of Chiefs of Police

(lACP) indicated that, of the 973 police departments that responded to the questionnaire, only

379, or 38.9 percent, used high speed pursuit

tires on their patrol cars. Table 1 gives the

number and location of departments that use

(or do not use) high speed pursuit tires.

Thirty-four percent of the responding police departments were located in the Western states,

which comprise Washington, Oregon and

California. Table 1 shows that 42.8 percent of the police departments that indicated they do

not use high speed pursuit tires are located in those states. It is interesting to note that 77.7

percent of the respondent departments in the

Western states do not use high speed pursuit

tires, yet there are many more miles of highways in those states than in some of the

other areas.

The following sections discuss the ways pursuit

tires are used, based on information obtained

from the lACP survey. Since only those police

departments that used high speed pursuit tires were asked to complete the questionnaire, the

discussions apply only to pursuit tire usage.

Types of Roads Driven

According to the survey, patrol cars travel over a variety of road surfaces on which they must

start, stop, turn, and sometimes travel at speeds in excess of 100 mph (160 km/h).

The amount of wear and tear placed upon tires

is dependent upon the types of roads within the

jurisdictions served by the police departments.

About half of the 379 police departments that responded indicated that 76 to 100 percent of the driving done by their patrol cars is on city streets.

About 40 percent of the police departments

stated that 1 5-25 percent of the driving done by

their patrol cars is on interstate highways and

state primary roads. About half of these police

departments revealed that poor tread wear is one of their most serious tire problems.

TABLE 1. DISTRIBUTION OF POLICE DEPARTMENTS THAT USE AND DO NOT USE HIGH

SPEED PURSUIT TIRES, BY GEOGRAPHIC AREA (1975)

Geographic Area

Police Departments Using

Pursuit Tires

Police Departments Not Using

Pursuit Tires Number of

Police DepartmentsPercent

of Area

Percent of Total Using

Number of

Police Department

Percent

of Area

Percent of Total Not Using

1. New England (80)* 45 56.3 1 1.9 35 43.7 5,9

2. Middle Atlantic (125) 54 43.2 14.2 71 56.8 11,9

3. East North Central (168) 70 41.7 18.5 98 58,3 16.5

4. West North Central (65) 41 63,1 10.8 24 36.9 4.0

5. South Atlantic (105) 45 42.9 1 1.9 60 57,1 10.1

6. East South Central (17) 11 64.7 2.9 6 35,3 1.0

7. West South Central (35) 19 54.3 5.0 16 45,7 2.7

8. Mountain (51

)

21 41.1 5.5 30 58,9 5.1

9, Western (327) 73 22.3 19.3 254 77,7 42.8

Total (973) 379 100 594 100 *Number of respondents. Source: 1976 I ACP survey.

2
Pursuit Driving

Pursuit tires are presently certified by certain

manufacturers for speeds up to 125 mph (200

km/h). The use of regular tires for pursuit

driving should never be considered, since the

Department of Transportation regulations

require that regular tires be certified for speeds

up to only 85 mph (136 km/h). Of the 379

police departments that use high speed pursuit

tires, 316, or 83 percent, do not abort high

speed pursuits after a specified distance; this further justifies the use of pursuit tires, since

sustained high speed places extra stress on

tires. A breakdown on these departments by

section of the country is given in table 2.

Tire l\Aaintenance

Failure to use high speed pursuit tires is not the

only danger faced by police departments

involved in pursuit work. Driving at high speeds

can be very dangerous if tire maintenance is poor. High speed driving will cause underinflated tires to run hot and will lead to tire failures. The survey results suggest that police department tire maintenance programs may need

improvement.

About half of the police departments that use

high speed pursuit tires indicated that mainte- nance checks on pursuit tires are performed

weekly or bi-monthly. The tire pressure is rechecked each shift, daily, or weekly by 65

percent of the police departments that use high

speed pursuit tires. The other 35 percent stated

that maintenance checks are only done as needed.

Only 25 percent of the police departments

indicated that tire damage, inflation pressure, and tread wear are checked during mainte- nance inspections of pursuit tires. Alignment is checked by 65 percent of the departments.

Less than 5 percent inspect balancing and

rotation during maintenance checks.

Pocket gauges, which are more accurate than

service station gauges [1], were used by 58

percent of the police departments to check infla- tion pressure. To assure that tire maintenance

procedures were being followed, 60 percent of the departments performed spot checks of tires. Only 4 percent, however, performed mainte- nance shop audits to assure that tire mainte- nance procedures were being followed and only

14 percent had written tire maintenance procedures.

TABLE 2. DISTANCES AT WHICH POLICE DEPARTMENTS ABORT HIGH SPEED PURSUITS (1975)

Geographic Area Do Not Abort

Distance

1 Mile 2 Miles 3 Miles 4 Miles 5 Miles More Than5 Miles

1 . New England 38* 2 1 2 0 1 1

2. Middle Atlantic 45 1 1 1 0 4 1 3. East North Central 58 0 3 1 0 3 5

4. West North Central 30 1 3 1 0 4 2

5. South Atlantic 38 1 2 1 0 1 2

6. East South Central 9 0 0 0 0 0 2

7. West South Central 18 0 0 0 0 0 1 8. Mountain 16 2 0 2 0 0 0

9. Western 64 3 1 0 0 5 0

Total 316 10 11 8 0 18 14

*Number of respondents. Source: 1976 lACP survey.

3
TABLE 3. MAJOR TIRE PROBLEMS OF POLICE DEPARTMENTS

BY GEOGRAPHIC AREA (1975)

Poor Tread Wear

Lack of High

Speed Endurance

-

Frequent Maintenance

vj cuyi u^lilv r\ lea

Police Departments

Number Percent

Police Departments

Number Percent

Police Departments

Number Percent

1. New England (45! 25 56 1 2 3 7

2. Middle Atlantic (54) 28 52 0 0 5 9

3. East North Central i70l 28 40 ~t o 4 15 21 Woct Mr»rfh P^antral lA 1 \ vvcsi iNOi in v^ctHiai \H 1

' 18 44 1 2 7 17

5, South Atlantic (45) 17 38 4 9 9 20

6. East South Central (11) 5 45 1 9 1 9

7. West South Central (19) 7 37 4 21 5 26

8. Mountain (21) 10 48 1 5 2 10

9, Western (73) 34 47 1 1 6 8

Total (379) 172 45 16 4 53 14

of respondents. Source; 1 976 I ACP survey.

The criteria for removing tires are relatively

consistent. More than half of the police departments stated that the reasons for removing

pursuit tires from patrol cars involved in pursuit

work are wear bar showing, minor damage,

cracked sidewall, chunking, blistering, or puncture.

Hazard Exposure

Driving on city streets places much more wear

and tear on tires than driving on highways. Cars

must constantly stop and go while driving on

city streets; they often come in contact with

curbs: and debris is found much more frequently on city streets than on highways. Frequent

cornering also causes increased tread wear.

Tat/e 3 shows how the police departments

responded to the question of what they

considered as their most serious tire problems.

Types of Tires Used

The responses from the survey showed that more police departments use steel radial-ply

and fabric radial-ply tires than belted bias-ply

and bias or cross-ply tires. Table 4 illustrates

this finding.

Tire Mileage

In addition to the numbers of responding police

departments that use the various types of tires, table 4 also gives the average mileage obtained

for each of the four types of tires. In 7 of the 9

geographic regions the departments averaged

1000 mi (1600 km) to 8000 mi (12,800 km) more from the belted bias-ply tires than from

the bias or cross-ply tires. In all the geographic

regions the police departments averaged more

mileage from the fabric radial-ply tires than from

the belted bias-ply tires. The departments

averaged more mileage from the steel radial-ply

tires than from the fabric radial-ply tires in 5 of the geographic regions.

Snow Tires

Because of the severe winters in some areas,

patrol cars may be equipped with snow tires for

4
over half of the year. This may encourage some

police departments to leave snow tires on patrol cars during the warmer months, with the as- sumption that this can save money. The cost of mounting and removing tires every fall and

every spring should not, however, be the only

factor that is considered. Other factors, such as

fuel economy during summer months and tread

life, are also important.

Laboratory tests conducted by Calspan Corporation for the Department of Transportation

revealed the following about the use of snow

tires during the summer months [11].

• Snow tires have greater rolling resis- tance than conventional tires, thus

reducing gas mileage by 2 percent.

• Snow tires have poorer cornering per- formance than conventional tires. This means that a car equipped with snow tires on the rear wheels is more

likely to spin out in a skid while

cornering on dry pavement, particularly at higher speeds.

TABLE 4. AVERAGE TREAD LIFE FOR EACH TYPE OF TIRE, BY GEOGRAPHIC AREA (1975)

Geographic area Bias or cross-ply No. Belted bias-ply No. Fabric radial-ply No. Steel radial-ply No.

1. New England 14,100 mi*

(22,700 km)

7** 11,700 mi

(18,800 km)

10 23,500 mi (37,800 km)

24 25,800 mi (41,500 km)

20

2. Middle Atlantic 12,800 mi

(20,600 km)

12 15,900 mi

(25,600 km)

13 17,300 mi (27,800 km)

28 21,200 mi (34,100 km)22

3. East North Central 15,200 mi (24,500 km)

9 18,300 mi (29,500 km)

21 24,200 mi (38,900 km)

38 24,100 mi (39,800 km)24

4. West North Central 13,500 mi (21,700 km)

10 14,700 mi

(23,700 km)

9 27,400 mi 44,100 km)

25 26,200 mi (42,200 km)22

5. South Atlantic 15,400 mi (24,800 km)

5 14,900 mi (24,000 km)

11 18,800 mi

(30,300 km)

32 19,500 mi (31,400 km)10

6. East South Central 10,000 mi

(16,100 km)

2 15,000 mi (24,100 km)

2 22,900 mi (36,900 km)

8 14,500 mi (23,300 km)2

7. West South Central 10,700 mi (17,200 km)

3 16,700 mi

(26,900 km)

7 26,200 mi (42,200 km)

14 33,800 mi

(54,400 km)

8

8. Mountain 13,800 mi

(22,200 km)

4 17,000 mi

(27,400 km)

9 25,600 mi

(41,200 km)

8 21,100 mi

(34,000 km)

10

9. Western

Total

10,000 mi

(16,100 km)

8

60

18,100 mi (29,100 km)

23

105

19,100 mi (30,700 km)

44

221

22,100 mi

(35,600 km)

24

142

*Mileage figures rounded to nearest 100. **Number of respondents. Source: 1976 I AGP survey.

• The stopping distance is greater for snow tires than for conventional tires, since snow tires develop less traction on dry roads.

• Since snow tires incorporate a rubber

compound that tends to remain

relatively soft in cold weather, they wear at a somewhat higher rate than

regular tires of the same construction

type.

Radials Versus Snow Tires

Radial tires, as a group, give superior rupture re- sistance, tread life, and cornering ability;

however, tests conducted by the National

Safety Council's Committee on Winter Driving

Hazards show that snow tires provide more

traction over a wide range of snow-covered

road conditions than conventional radial tires that do not have snow treads. The Committee

also stated that radial tires offer no advantage

over conventional tires in either stopping,

traction or cornering performance on glare ice.

5
TECHNICAL ASPECTS

Construction

Purchasers of pursuit tires have a choice of

three types of tire construction. Although all pursuit tires look similar on the outside, on the

inside the various types—bias-ply, bias-belted,

and radial—differ markedly. Basically, every tire consists of beads, a carcass, and a tread. The

tread provides the traction. Manufacturers

produce a variety of tread patterns to meet

various driving requirements. The carcass is the

body of the tire. The beads are the two edges

of the tire, reinforced with steel cable, that

contact and seal the tire against the wheel rim.

Bias-Ply

The bias-ply is the oldest and most familiar type

of tire in this country. Its carcass, underneath

the rubber skin, consists of fabric layers or plies

which run at about a 35° angle to the direction

of travel (fig. 1a). The bias-ply tire has an equal

number of plies in the tread and sidewalls. It provides a soft, quiet ride, but the relative lack

of stability in the tread area causes the tread to

distort and squirm on contact with the road,

resulting in more rapid tread wear.

Bias-Belted

The bias-belted tire combines the diagonal

layers of the bias-ply tire with a 2-ply belt under

the tread (fig. lb). The result is a tire with

improved tread mileage, better traction, and more protection against punctures and bruises

than the bias-ply tire.

Radial

The radial tire has plies that run at right angles

to the tread (fig. 1c). The sidewalls are more

flexible than bias-ply sidewalls, and give a better

ride, readily absorb impacts, reduce squirm, and

provide a cooler running tire. This tire construction also gives superior performance in the areas of tread mileage, wet skid protection, and

steering. FIGURE 1c

6
Tire Markings

As specified in Motor Vehicle Safety Standard

No. 1 09, each tire has molded into or onto both

sidewalls the size designation, the maximum permissible inflation pressure, the maximum load

rating, the name of each cord material, the

actual number of plies in the sidewalls and the

actual number of plies in the tread area if different, the words "tubeless" or "tube type"

as applicable and the word "radial" if the tire is a radial-ply tire.

The following explanation of the markings on a GR70-15 tire (fig. 2) is based on that given in the B. F. Goodrich Passenger Tire Manual [6]. GR70-15—Tire Designation

G—Size Designation

Letters are used to designate tire size,

and have an important bearing on load

carrying capacity. A G-size tire is designed to carry a load of 1 380 pounds

at 24 psi inflation, and a maximum load

of 1620 pounds at maximum air pressure of 32 psi, for Load Range B. In comparison, a G-size, Load Range D

tire can carry a maximum load of 1830

pounds at a maximum pressure of 40

psi. The load carrying capacities were

established by The Tire and Rim Association, Inc., and are given in appendix A. As shown in that appendix, the load

carrying capacity of a tire in a specific

letter size is dependent on the inflation pressure; its load carrying capacity can

be increased by raising its inflation pressure. The maximum inflation pressure which a tire can carry is controlled by its load range. Maximum

load and inflation pressure are branded on the tire sidewalk

For a specific letter size (G in this case)

the carrying capacity is the same for all tires irrespective of rim diameter, series

(aspect ratio) or type of construction.

FIGURE 2
FIGURE 3. TIRE PROFILES BY SERIES (NOT TO SCALE)

R—Radial

The 'R' means that this tire is a radial

tire.

70—Series

The 70' indicates that the height of the

tire is 70 percent of its width. The lower

the number, the wider and lower the tire

(fig. 3). The tread width is proportional

to the tire width.

15—Rim Diameter

The '15' indicates that this tire is designed for a 1 5 inch diameter wheel.

Load Range

The load range identifies a given size

tire with its load and pressure limits. As stated previously, the load range of a

tire affects its maximum load carrying

capacity. Most passenger tires are Load

Range B and are restricted to a maximum load which can be carried with the

maximum inflation pressure of 32 psi.

Where greater load carrying capacity is needed. Load Range C or D tires may

be used. These can withstand higher

maximum inflation pressures and carry greater loads.

Formerly, the term 'ply rating' was used

instead of 'load range.' Confusion arose from trying to equate the ply rating with

the actual number of plies in the tire. An

example is 4-ply vs. 4-ply rating/2-ply.

Both tires had equal strength and load

and inflation ratings, but the actual

numbers of plies differed. The tire industry therefore adopted the term

'load range' to replace 'ply rating.' The

letters B, C, and D identify the load

ranges of most passenger car tires. They correspond to the former 4-, 6-, and 8-ply ratings, respectively.

Tread Piles-Sidewaii Piles

Every tire has markings to reveal the

cord material and the number of plies in the body and in the belt (if it's a belted

tire). The tire shown in figure 2 has a

total of four plies, including two body

plies and two tread plies.

DOT

These are the initials of the Department

of Transportation, the Federal agency

that sets tire standards. They denote

that the tire meets or exceeds Federal

requirements. Following this symbol is a

serial number which identifies the tire manufacturer, manufacturing plant, type

8
of tire construction and date

manufactured.

Pursuit Tires

Pursuit tires have an added identification which

distinguishes them from regular tires. Some

examples are: "Patrol," "Police Special," "High

Speed Pursuit," etc.

Tire Materials

The cords are the strands that form the plies in a tire. The tire cord is the backbone of a tire because it is the major source of its strength.

The cords provide bruise and fatigue resistance,

comfort, and maneuverability. They can also

contribute to improved tread wear resistance. In spite of the fact that tire cords play such a signif- icant role, they are only about ten percent of the

weight of the tire.

Rayon, nylon, and polyester are the fabrics

commonly used in tire carcass plies. Rayon is the oldest of these materials and provides a smooth ride at all speeds. It is preferred as the carcass cord in radial-ply tires because of its excellent flex fatigue resistance. Nylon is one of the strongest and coolest-running tire cord

materials, providing the greatest protection

when speed and loads are severe. Polyester

has the strength of nylon and is preferred for passenger tire carcasses because of its superior ride qualities.

Rayon, nylon, and polyester are also used as

belt cords. Rayon makes an excellent material

for radial tire belts because of its dimensional

stability and its good ride characteristics. Steel

wire and fiberglass, due to their stiffness, low

stretch, and high strength, are also used very

effectively in belts to provide good tread wear. They also reduce tread scuffing and provide

added protection against bruises and impacts.

Aramid is a new fiber developed specifically as

a tire cord. It is stronger and lighter than steel,

yet it will not stretch, shrink, grow, or distort like other fibers.

Use of Chains

There are several misconceptions about radial

tires, both favorable and unfavorable. One is the

belief that the sidewalls of a radial tire are more

susceptible to damage from chains than those

of bias or bias-belted tires.

Tests made by the United States Auto Club

(USAC) for the National Association of Chain

Manufacturers [9] show that this is not the case. The USAC tests were run at a sustained speed

of 35 mph (56 km/h) on bare pavement, and

even after a distance of 150 mi (240 km)

showed no evidence of sidewall damage to any

of the radials tested. However, driving for as

little as 15-20 mi (24-32 km) on dry pavement

caused the original equipment bias-ply and

belted-bias tires tested to develop severe

sidewall and tread gouges. This did not occur on wet pavement, indicating the lubricating effect of moisture. Correct chain size, proper fit, moderate driving speeds and minimal driving on

dry pavement are essential for long life and max- imum performance of both tires and chains.

Tires and Gasoline Mileage

A study conducted for the U.S. Department of Transportation [11] showed that the use of

radial tires on automobiles can improve gasoline

mileage over either bias-ply or bias-belted tires. The rolling resistances of 35 different tires of the three basic constructions, of various carcass and belt materials, design loads and

height-to-width ratios, were measured. The tests were conducted on a tire tester which

accurately simulates actual highway conditions.

The rolling resistance losses of a tire do not produce useful work and are dissipated mainly

in the form of tire heat. A reduction in these tire energy losses thus increases fuel economy.

Though there were differences between tire brands of the same construction type, the study

showed that under normal driving conditions

radial-ply tires provide about 6 percent better

fuel economy than bias-ply tires.

9
SELECTION AND PURCHASING OF TIRES

Principles of Selection

Tires for patrol cars should be selected on the

basis of how they will be used. For example, it would be wasteful to put high speed tires on

patrol cars that seldom exceed 60 mph (96

km/h) and never exceed 75 mph (120 km/h).

IT IS IMPORTANT TO REMEMBER THAT

REGULAR PASSENGER CAR TIRES SHOULD

NEVER BE PURCHASED FOR USE ON

PATROL CARS INVOLVED IN PURSUIT

WORK. Regular passenger car tires, of all grades and constructions, are not suitable for high speed police use. Tests conducted by the

U.S. Department of Transportation showed that such tires failed at average speeds of 100 mph

(160 km/h) when tested on a high speed drum

[3]. An analysis of their data is given in table 5. Patrol cars which may be used in sustained high

speed driving should be equipped with tires that are certified by the manufacturer for use at speeds of at least 125 mph (200 km/h).

Cost Factors

There are many different factors to be

considered in buying tires. Cost is one important

factor. However, the lowest-cost tire may not be

the cheapest tire. Some police departments

purchase tires on the basis of low bid only.

Many use this method believing that there are no alternatives or that justification for departing

from low bid is too difficult. Others use the low

bid method because the economics of buying

tires are not considered. Tire cost goes beyond

the purchase price. A tire that costs $30 and

lasts 12,000 mi (19,200 km) is just as expensive as one that costs $100 and lasts 40,000 mi

(64,000 km). In fact, when the cost of removing,

replacing, and balancing tires is considered, the

$30 tire is far more expensive.

Tire warranties, another factor to consider, vary

considerably from manufacturer to manufacturer. Some warranties on tires are for specified

miles against tread wear and road hazards

based on the car's odometer readings. This means that if the tire wears out or fails after the

odometer shows the tire rolled only 75 percent i of the miles specified on the warranty, a 25 ! percent credit is given toward a new tire. Other j companies have the same policy in connection i with tread wear, but their road hazard warran- i| ties operate differently. If the tire fails, the ! dealer measures the tire's remaining tread

depth and bases the adjustment on the

percentage of tread that has worn away,

regardless of how many miles the tire has been

driven. Also, dealers may not honor a warranty

if the cause of the tire wear appears to be

improper wheel alignment or failure to perform

recommended rotation. d

c

In addition, when evaluating tire expenditures

for pursuit applications, factors such as safety ^

of personnel and equipment, vehicle control 1 under emergency conditions, and the potential j economic cost of a disastrous tire failure must i be considered. I

\ Performance

| In addition to being designed for speeds up ' through 125 mph (200 km/h), a pursuit tire should provide good traction for starting,

stopping, and cornering, be strong enough to

j withstand the usual road hazards, and give long wear. To meet these requirements tires need to

{ be selected with care; however, there is rarely i enough information on hand to make this possible. Just as there is no one tire that is the

most economical for departments with different requirements, there is probably no one tire at any price that is the best overall performer.

Compromises have to be made on the conflic- ting requirements of cost, ride, handling, highj speed endurance, tread wear, resistance to ! damage, rolling resistance, traction under

various driving and braking conditions, etc. ' Some tire manufacturers might, for example,

favor a smooth quiet ride in preference to handling precision, while others might favor wet- > road safety over long tread life.

In order to measure the variation in the wet

traction performance of pursuit tires made by i

10
different manufacturers, tests were conducted

for the Law Enforcement Standards Laboratory

by the Safety Research Laboratory of the U.S. Department of Transportation [5]. They performed braking, cornering, and driving traction tests using modified ASTM procedures.

The tires tested for wet traction are described in table 6, and the test results are given in table 7. Though the tires are ranked from 1 through 10, some of the differences in rank are not signifi- cant. Measurements underlined by a common

line do not differ significantly from one another

in the statistical sense, and identify tires of equal rank. Those entries to the left or right of an underlined group do differ significantly, at the

0.05 confidence level, from those in the underlined group.

Braking Traction

The conclusions presented here are based on

the stopping distance data.

• The Goodyear Flexten tire performed

better than any other tire in the

braking test, stopping in 420 ft (128

m). If a police car using four of these

tires were to lock its brakes on a 50.2

SN (skid number per ASTM E 274-70)

surface, the car would stop in 210 ft (64 m). (Since sets of two tires were

braked in the test, the stopping

distance must be divided by 2 in order

to obtain the equivalent result for 4

wheel braking.)

• The average stopping distance for the

tires in the next group, sets 2, 4, 9, 1 and 8, was 449 ft (137 m). Thus, the

increase in stopping distance due to the use of the second best rather

than the best tires would be 29 ft (9

m), or 7 percent.

• Set 6 performed poorest, with a

stopping distance of 499 ft (152 m);

there is thus a difference of 19

TABLES. TIRE FAILURES, BY CONSTRUCTION* [3]

Speed At Failure**

Construction mphkm/h

80

129

85

137 90145

95

153

100

161 105169 110177

115

185 120193

Did Not

Fail

Average

Speed at Failure

Total Number

of

Tires Tested

Bias ply 11 4 14 5 1 2 101 mph

(162 km/h)

27

Bias belted 2 4 6 2 4 1 3 2*** 101 mph

(163 km/h)

24

H

Fabric radial 1 4 2 1 3 (100 mph

(161 km/h)

11

Steel radial 1 1 2 9 10 1 101 mph

(162 km/h)

24 % Total 86

*This analysis is based upon data provided by the Safety Research Laboratory, U.S. Department of Transportation. Tires were standard grade passenger tires selected from stocks on hand. The data were obtained from tests conducted on a high speed drum, and may not reflect failures at these speeds on open road operations.

**DOT Test Procedure; Break-in at 50 mph (80 km/h) for four hours; cool tires to ambient temperature (100°F

or 37.8°C); run tires for 30 minutes at 75 mph (121 km/h); increase speed in 5 mph (8 km/h) increments and run

for 30 minutes at each new speed until failure occurs. ***Two tires withstood 30 minutes at 120 mph (193 km/h) without failure; the tests were suspended at that point. For averaging purposes, these were assumed to have failed at 125 mph (20 km/h).

11
TABLE 6. DESCRIPTION OF POLICE TIRES, IN ORDER TESTED [5]

Set No. Make* Serial Number Size Construction Material

Sides Tread

1 Armstrong CEU6A51 176 H70-15 Bias 4 Ply Nylon

4 Ply Nylon

2 Dunlop Gold

Seal DAVXA53176 H78-15 Bias - 4 Ply Nylon

4 Ply Nylon

3 Dunlop Elite DBVYA2A HR78-15 1 1 au 1 a 1 — "? PIv Pnlupctpr 2 Ply Aramid

2 Ply Nylon

4 Goodrich

Pursuit

Radial

BEU7LL2 475 HR70-14 Radial — 2 Ply Rayon

6 Ply Rayon

5 Goodyear

Flexten

l\/IKU73FH 156 HR70-15 Radial - 6 Ply Polyester 4 Ply Aramid

6 Goodyear

Police Special

MBVXPAA 066 H78-15 Bias - 4 Ply Nylon

4 Ply Nylon

7 Michelin FHTVA2FX215

FHTVA1FX 245

FHTVA2FX 245

FHTVA2FX 215

215HR15XVS

(HR78-15)

Radial 2 Ply Rayon

2 Ply Rayon

2 Ply Steel

8 Pirelli XBTUXKLK 095 215HRCN75

(HR78-15)

Radial 2 Ply Rayon

2 Ply Rayon

9 Pl\/ Qtool z riy oteei 2 Ply Nylon

9 Firestone VCVYW77166 HR78-15 Radial 2 Ply Polyester 2 Ply Polyester 2 Ply Aramid

10 Firestone Super 125 VCU7W77136 HR70-15 Radial 2 Ply Polyester 2 Ply Polyester 2 Ply Aramid

*The use of brand names in this report in no way constitutes endorsement of these products by the National Bureau of Standards or any other agency of the Federal Government. Since not all brands of tires were submitted by their manufacturers for high speed testing, the omission of any brand from this report should not be construed as indicating that the brand is either unsafe or inferior in quality, nor should the

inclusion of a brand be construed as evidence that future production runs of that tire will perform in the same manner as those tested.

12
TABLE 7. RANKING OF 10 PAIRS OF POLICE TIRES FOR BRAKING. CORNERING,

DRIVING AND SPINNING TRACTION [5]

Rank 10

Tire Set No.

Stopping distance (ft), at 60 mph

Relative traction (%)

Braking Traction^ 52491 83 10 76

419.7 440.2 440.8 451.8 454.0 456.1 460.8 464.6 475.9 499.0

108.0 103.5 103.4 101.0 100.5 100.0 99.0 98.2 95.7 90.6

Tire Set No.

Cornering traction

coefficient

Relative traction (%)

Cornering Traction 8795 10 243 1 6

0.576 0.554 0.550 0.549 0.545 0.535 0.533 0.527 0.513 0.490

107.2 103.1 102.4 102.2 101.5 99.6 99.2 98.1 95.5 91.2

Tire Set No.

Peak driving traction

coefficient

Relative traction (%)

Driving Traction 84975 10 36 1 2

1.197 1.149 1.131 1.123 1.120 1.109 1.090 0.918 0.873 0.864

113.2 108.7 107.0 106.2 105.9 104.5 103.1 86.8 82.6 81.7

Spinning Traction

5 10 79346821 0.904 0.869 0.858 0.853 0.843 0.837 0.825 0.812 0.770 0.753

Tire Set No.

Spinning traction

coefficient

Relative traction (%) 108.6 104.4 103.1 102.5 101.3 100.6 99.1 97.5 92.5 90.5

Tested per ASTM F403-74.

•Tested per ASTIVl F376-73.

^Tested per ASTM F424-75.

13
FATAL HIGH SPEED FAILURE OF STANDARD GRADE PASSENGER TIRE

(ALABAMA STATE POLICE - 1974)

percent between the best tire (set 5)

and the worst tire (set 6).

• The radial tires braked slightly better

than the bias-ply tires; the average

stopping distance for the bias-ply tires was 464 ft (141 m) vs. 453 ft (138 m)

for the radial tires, a difference of 2

percent.

• The 70 series tires braked better than

the 78 series tires; the average

stopping distance for the 78 series

tires was 464 ft (141 m) vs. 445 ft (136 m) for the 70 series tires, a

difference of 4 percent.

Cornering Traction

• The cornering traction test divided the

tires into four groups. The set 6 tires performed significantly poorer than

any of the other tires. On a 200 ft (6l

m) radius curve, the maximum speed

would be 38 mph (62 km/h).

• The radial tires cornered better than

the bias-ply tires. The average

cornering coefficient for the bias-ply

tires was 0.51 vs. 0.55 for the radials. This represents an 8 percent better

performance by the radials. In other

words, a car could negotiate a 200 ft (61 m) radius curve of the test pavement with radial tires at 41 mph (66

km/h), and with bias-ply tires at 39

mph (63 km/h).

• No significant difference was found

between the cornering performances

of the 70 series and the 78 series

tires.

Driving Traction

• The radial tires performed better as a

group than the bias-ply tires in wet

driving traction.

• There was no significant difference

between 70 and 78 series tires in wet

driving traction.

Endurance and Tread Wear

The General Services Administration has

recently conducted endurance and tread wear

performance tests on police pursuit tires. The

data obtained from these tests enabled them to compile the Qualified Products List shown in appendix B. Certain brands that appear on this

list were not tested for traction, and vice versa.

14
OPERATIONAL ASPECTS [2, 12]

Installation

Once the proper tires have been selected, the

job is not ended; good service practices are

also important. These include mounting and bal- ancing the tires, wheel alignment, tire rotation,

and timely replacement.

Mounting Tires on Wtieels

Before new tires are mounted, the wheels

should be visually inspected to make sure they

are in good condition, and the tires should be

inspected for defects in material and workmanship. The following are procedures to follow

when mounting a set of new tires.

• Remove old balance weights.

• Carefully clean the tire beads and the

bead seat areas of the wheel of dirt and rust. This will help to insure an

airtight seal between the tire and the

rim.

• Replace old valves with new ones. It

is recommended that metal clamp-in

valves be used instead of the rubber

snap-in type. During high speed runs

air loss can occur through the tire valve due to centrifugal force. To

prevent this, dome seal type valve

caps should be used.

• Thoroughly lubricate the side and

base of the tire beads as well as the

rim bead seat ledges with an

approved mounting solution, thin vegetable oil, soap, or plain water, before

putting the tire on the rim. Under no

circumstances should they be

mounted dry, nor should antifreeze,

detergents, brake fluid or other petroleum base liquids be used.

• In mounting the tire push the bottom

bead in the well of the wheel to prevent tearing of the beads. The

side of the wheel with the narrow

ledge must be facing up.

• To start mounting the top bead, push

that portion of the top bead directly In front of you down into the wheel well and hold it there while the machine

runs the remainder of the bead onto

the wheel.

• There are several types of bead

expanders on the market and it is rec- ommended that one be available for hard-to-seat beads. One method of seating beads without a bead

expander is as follows: Position the

tire-wheel assembly so that the valve

is facing down. Press the upper bead

by hand against the lower bead on

the lower ledge of the wheel. Turn the

assembly over with the valve facing

up. If the lower bead has been forced on sufficiently tightly, this bead will now stay on the topside of the wheel

and the loose bead will fall down

against the lower edge, effecting a

seal so that the tire can be inflated.

• Inflate the tire in the usual manner.

For safety, install the valve core in the valve stem before attempting to

inflate the tire. Proper seating of the

beads may require initial inflation pressures higher than operating

pressures, but these should never exceed 40 psi (276 kPa). After the

beads are seated, reduce the

pressure to the proper operating

pressure.

• While standard mounting machines

and tools can be used for mounting

radial tires, special precautions must

be taken to see to it that the tire beads seat properly against the rim

flanges. The seating is more difficult than for tires of other construction,

and can be checked by sighting the

circumferential ridge on the tire just

above the flange area to see if it Is visible and running parallel to the rim

flange all the way around.

15

Inflation Pressure

Maintaining the proper inflation pressure is one

of the best ways of realizing the advantages

and benefits of pursuit tires. This will assure that the tires will carry the specified weight; provide

maximum traction in a curve or corner; resist damage from rocks and potholes; and squirm

less and run cooler than at lower pressures.

Tires should be inflated to the pressure recom- mended by the car manufacturer or the tire manufacturer. The air pressures recommended

are always the cold inflation pressures, i.e., those obtained during installation or after the

car has been parked for several hours.

Appendix A gives the maximum permissible air pressure and load range for a given tire size. Underinflation can greatly shorten the life of a

tire and can cause internal tire damage and

failure in extreme cases. Underinflation also causes rapid wear on the outer edges of the

tread. As can be seen in figure 4, underinflation

has a significant effect on the contained-air

temperature of tires. Overinflation can also cause internal damage to tires and causes them

to wear faster at the center of the tread.

After the tires are mounted and inflated, the

following services should be performed.

• Dynamically balance all four wheels.

High speed tires should not be

balanced using static methods

(bubble balancing).

• Set front wheel toe-in to the value

established by the car manufacturer

to achieve the best vehicle and tire performance.

km/h

300

UJ

ccD

H

<

DC

LUa.

Sicc 200 —

<Q

111 Z

<

H

Z

O

o

250 —

150 —

200 — 140

120

100

QCD

H

<

OC

LUIcc<

Q

80 5<O

a — 60

125

TEST DRUM SPEED - mi/h

FIGURE 4. RELATION OF CONTAINED-AIR TEMPERATURE AND TEST

DRUM SPEED AT 24 PSI AND 32 PSI [8]

17
FIGURE 6.

• Check camber and caster to make

certain they are set within the car manufacturer's specifications.

• Check shock absorbers, wheel

bearings, steering components, and

brakes to make certain they are in good condition and functioning

properly.

Radial Run-Out

Wheel vibrations are usually attributed to unbalanced or improperly balanced tires, but

the unbalance component due to radial run-out

(out of roundness) has often been ignored. To

assure optimum performance, however, radial run-out should be minimized. The radial run-out gauge (fig. 5) is a precision instrument used to measure wheel and tire out-of-roundness, the

distance between the high and low points

around the circumference.

The following procedure should be used to measure and minimize radial run-out:

• Newly installed belted-bias or radial

tires usually do not require warm-up.

However, if the tires are to be

warmed up to eliminate any possible

flat spots, the car should be driven for a distance of at least 6 mi (10 km).

• Jack up the car immediately to avoid

the development of flat spots and to allow all four wheels to run freely.

• Place the run-out gauge in front of the

tire and wheel assembly to be

checked so that the rotating disc on

the end of the plunger is in contact

with the tire (fig. 6). On new installa- tions the radial run-out should be

checked on the second tread rib in from the outer edge.

• Rotate the tire slowly, stop at the

point where the gauge reads closest

to zero, and adjust the reading to exactly zero. Rotate the tire once to confirm that this is actually the lowest

spot on the tire and then mark this radius on both the tire and the wheel

with the letter "L."

18
TIRE REPOSITIONED ON WHEEL

FIGURE?. MINIMIZIIMG RADIAL RUIM-OUT

• If the overall run-out is still over 3/64

in (1 .2 mm), check the radial run-outs

of each bead seat on the wheel

(without tire) to help decide whether

the wheel or tire should be repaired

or replaced.

Balancing

After their radial run-outs are minimized, the

wheel assemblies must be balanced. If this is not done properly the resulting vibration will increase tire wear and will also cause excessive wear in bearings, ball joints, drive shafts, etc., and substantially reduce their service life. This

is especially true in vehicles that are driven at greater than average speeds or at the

resonating speed of the wheel/tire assembly.

There are three basic types of unbal- ance: static, couple, and dynamic.

• Static unbalance (fig. 8), formerly also

called force or kinetic unbalance, causes "wheel hop" or "bounce." In

its simplest form, the total unbalance

• Rotate the tire slowly and note the

amount of variance from zero on the

gauge. Locate the highest point and

mark both the tire and the wheel with

the letter "H."

• The maximum run-out of each wheel

and tire combination should be

determined and recorded.

• If the radial run-out is 3/64 in (1.2

mm) or less, proceed to balance the

tire in the usual way. If it is over 3/64

in (1 .2 mm), attempt to minimize it as

follows:

• Mark one of the wheel studs and the

bolt hole using that stud.

• Reposition the wheel assembly on

the hub so that the marked stud and

bolt are as far apart as possible.

• If the radial run-out still exceeds 3/64

in (1 .2 mm), reposition the tire on the

wheel so that the previously marked

high point on the tire (H) coincides

with the low point on the wheel (L)

(fig. 7).

19
UNBALANCE

(HEAVY SPOT)

CORRECTION

WEIGHT

CORRECTION

WEIGHT

FIGURE 8

UNBALANCE

CORRECTION

WEIGHT

FIGURE 9.

CORRECTION

WEIGHT

UNBALANCE

UNBALANCE--4S

UNBALANCE

FIGURE 10.

mass is located in one spot

equidistant between the two rims of the wheel. It can be corrected by

placing equal weights of the proper

size on each side of the wheel

exactly 180° opposite the location of the heavy spot.

• Couple unbalance (fig. 9), sometimes

called moment unbalance, causes

"wheel wobble." In one form, two

unbalance masses are positioned on

opposite sides of the tire and spaced

180° from each other. It can be

corrected with two weights placed on

opposite sides of the wheel and 180°

from each other. In other words, a

couple unbalance needs a counter- couple to correct it.

• Dynamic unbalance (fig. 10) is a combination of static and couple

unbalance and is found in nearly all wheel assemblies.

Before any balancing is attempted, mud and dirt must be cleaned from the wheel and tire. Another rule is to split the weights to be applied

whenever the amount required exceeds one

ounce.

The functions of a balancing machine are to

20

I
BALANCING HEAD

SPINNER

FIGURE 11.

determine whether a wheel assembly is out of balance and, if it is, to indicate the amount of weight that must be added, and the location at which it must be added to bring about balance.

There are basically two types of on-car

balancers, the mechanical type and the

electronic type. In using either type it is important to remember that limited slip differentials require that both rear wheels be off the ground

during balancing.

Mechanical On-the-Car Balancer (fig. 1 1)

These balancers are often erroneously referred

to as dynamic balancing systems; however,

most of them are only designed to correct static unbalance. A few can also detect couple

unbalance, but are rarely operated in that mode.

Most of these balancers use a hubcap-type bal- ancing head containing movable weights. This

balancing head must be carefully secured to the

rim to prevent the fixture itself from introducing

unbalance into the system. After the car is raised off the floor a separate motor-driven

spinner is used to spin the non-drive wheels.

Those cars having disc brakes require a 3 hp

(minimum) wheel spinner to achieve the proper

amount of wheel spin. Drive wheels without

limited slip differentials can be spun by allowing one wheel to remain on the ground or blocked

while the other is driven by the engine. In this instance 35 mph (about 55 km/h) on the speedometer equals 70 mph (about 110 km/h). On

vehicles with limited slip differential both wheels

must be off the floor and the car should be ac- celerated to a maximum of 80 mph (130 km/h) on the speedometer, which is also 80 mph

wheel speed. In both cases the acceleration

should be gradual. The spinning, unbalanced

wheel assembly is then allowed to coast and

the weights in the balancing head are adjusted

until the vibration caused by the unbalance is reduced to a point where the operator, either by

sight or touch, determines that operation is smooth. The permanent weights are then

attached at the positions indicated by the

adjustable weights inside the balancing head.

After the initial spin balance, the balancing head

should be removed and the wheel spun again to check for vibration. If vibration is present on a

freely spinning wheel, it may be due to static unbalance (caused by removal of the balancing

mechanism) or by couple unbalance (which the

balancer was never able to correct in the first place). Additional balancing weights should then

be placed on both the inside and outside of the

wheel, by trial and error, until smooth operation

is achieved.

21
mounted either horizontally or vertically,

depending on the design of the balancer (fig. 13). The horizontal mounting machine has an advantage in that the wheel is better able to center itself. Most dynamic balancers provide an unbalance readout combining static and

couple unbalance into a dynamic reading. This

enables the wheel assembly to be balanced by

adding one correction weight to each side of the wheel. The major advantage of this machine

is that generally a wheei can be balanced faster and to a finer degree than with a bubble, static, or on-the-car system.

FIGURE 12.

Electronic On-the-Car Balancer

This device (fig. 12) utilizes a displacement

measuring vibration pick-up which is placed

under the car in a position to measure vibration

either vertically (static) or horizontally (couple).

A strobe light is used to determine the angle of unbalance and a meter indicates the approximate amount of unbalance correction. The

wheels are spun as with th6 mechanical

balancers. Front wheels can be balanced to remove static and couple unbalance separately,

thereby attaining dynamic balance. The rear wheels, however, can only be measured for

static unbalance.

Wheels can usually be balanced for smoother

operation with this machine than with a bubble

or static balancer; however, the operator using

this machine plays a more significant role. He

must know how to interpret the meter readings

during a momentary peak while the wheel

coasts down through a resonance which may

be affected by the tightness of the front end

linkages, by variable damping from shock

absorbers, wheel bearings, dragging brakes,

etc. Getting under the car repeatedly to attach

or change trial weights and to change the pickup position requires considerable patience.

Off-the-Car Dynamic Balancer

This is a machine capable of rotating a wheel

assembly at high speed. The wheel assembly is

FIGURE 13a. HORIZONTAL OFF-THE-CAR

DYNAMIC BALANCER

FIGURE 13b. VERTICAL OFF-THE-CAR

DYNAMIC BALANCER

22
Alignment

Improper alignment of the front wheels with

respect to the direction of travel is another

factor which can cause excessive wear. The

three angles associated with alignment, shown

in figure 14, are camber, caster, and toe-in.

Camber is the inclination of the wheel from the

vertical. Caster is the inclination from the

vertical of the axis through the ball-joints or king

pins. Caster causes the front wheels to straighten after a turn. It also helps counteract

the tendency of a car to wander due to wind or uneven road surfaces. Camber and rolling resis- tance tend to force the front wheels outward at

their forward edge. To compensate for this tendency, the front wheels are turned slightly

inward (i.e., toe in) when the car is at rest.

Tires worn primarily on one side indicate a

problem with toe-in or camber. If toe-in is incorrect on one wheel, the car will probably

pull to one side or the other. If toe-in is incorrect on both wheels, the car is probably hard to steer in either direction. Tire cupping can result from worn shock absorbers, one wheel out of alignment, a bent spindle, or a combination of these.

Safety Precautions

There are several safety hazards associated

with mounting and inflating tires that are sometimes overlooked by service personnel. To

help prevent serious personal injury or tire damage when mounting automobile tires the

Tire Industry Safety Council recommends the

following:

• Make certain that the valve core is inserted in the valve stem prior to

inflating. If this is attempted after infla- tion, the valve can become a danger- ous projectile.

• Use an extension gauge with a clip- on chuck during the bead seating

process (fig. 15) so that the air pressure buildup can be closely

watched while standing well back

from the tire.

• Wear safety glasses or goggles.

FRONT VIEW

< = TOE-IN

TOP VIEW

ANGLE 7 = CASTER ANGLE OF STEERING KNUCKLE

SIDE VIEW

FIGURE 14. CAMBER, TOE-IN, AND CASTER:

THE ALIGNMENT ANGLES

23
PRESSURE INDICATOR

CLIP-ON CHUCK

FIGURE 15

Operations

There are many factors that can affect the per- formance of tires. Below are some suggestions

to keep in mind in order to get the best perfor- mance from pursuit tires.

Break-in

Break-in is needed because of the greater

amount of heat generated during initial flexing.

High-speed tires, like regular tires, need a

break-in period. They should be broken in by

driving 55 mph (90 km/h) for the first 50 mi (80

km). This will help to avoid possible damage to the tires by giving the various parts of the tires a chance to "seat in."

inflation and Loading

Keeping tires properly inflated for the load

carried is very important for tire safety and

wear. The load which a tire will safely carry depends on its size, its load range or ply rating,

and its inflation pressure. The load range table

(appendix A) gives the load limits (pounds per

tire) for tires normally used on passenger

vehicles. In order to use the table, first check

the Car Owner's Manual for the normal weight

of the car, add the additional weight the car is expected to carry, and divide by four. This will give an approximation of the weight per tire.

In the row where the tire designation appears

(for example, G78-15), look under the load

range section for the maximum load each tire is

expected to carry. The figure at the head of theu column is the correct cold air pressure for a tiresj carrying a particular load. The tires should be I inflated cold to an air pressure which is at least \ as high as the value given in the table.

Thus, Load Range B tires are for pressures of 32 psi (220 kPa) or under; Load Range C tires are for pressures of 36 psi (248 kPa) or under

and Load Range D are for pressures of 40 psi

(276 kPa) and under. This information is also

marked on the sidewalls of all new tires; for example, "max. load 1620 lb @ 32 psi max.

pressure."

Road Conditions

Broken cords in the rim area of a tire may be

caused by a severe blow. This usually occurs from the impact of a tire hitting a curb or chuckhole. This type of injury to a tire is not

repairable. Broken cords directly under the

tread are caused by sharp head-on impact. The

position and size of the break is determined by

the angle and force of the impact. To avoid

these and other damages such as cuts, bruises

and blowouts, slow down on bad roads, and

avoid driving over curbs and other obstructions.

Driver Habits

Driving habits have a direct bearing on tire wear. Using brakes more than necessary

increases tire wear. Some ways to avoid this are to use the engine compression to help

24
decelerate and to slow down before reaching a

corner. When a sudden stop has to be made

avoid locking the wheels. A locked wheel panic

stop not only wears tires severely and unevenly,

; but reduces stopping ability and may cause one

I to lose control of the car. Rapid starts, driving at excessive speeds, and riding the edge of the

pavement all tend to wear away tread rubber

rapidly.

Mechanical Condition of Vehicle

I Maintenance of the vehicle in good mechanical

condition not only improves its riding characteristics and safety, but also helps in gaining maximum tire mileage by reducing irregular wear. Misalignment of the front wheels, rear wheel

misalignment due to a sprung axle housing or a

i bent wheel, worn bushings, faulty or "grabbing"

brakes, and faulty or worn shock absorbers conFIGURE 16. STATES OF TIRE INFLATION

tribute to uneven and rapid tread wear and

should be corrected.

Maintenance

In order to get the maximum wear and perfor- mance from a tire, it is important to perform the

necessary maintenance. Good maintenance can eliminate most tire trouble, and at the same

time help to promote safety on the highway.

Although Inflation, balance, alignment, and

rotation are not the only factors to consider,

they should be the main factors in any mainte- nance program.

Inflation Checks

Because of the extremely high speeds at which

patrol vehicles may be driven, tire manufacturers recommend that their tires be inflated to the

maximum allowable "cold" pressure for the appropriate load range. Using the maximum

allowable pressure reduces tire deflection and

heat buildup and allows tires to operate in a

satisfactory temperature range. Pressure should

be checked daily with an accurate pressure

gauge.

The readings of air hose pressure gauges at service stations should not be relied upon. They

are not subject to regular testing or any kind of

certification for accuracy and are often seriously

inaccurate. Tests in 1971 by the National

Bureau of Standards [1] revealed that approximately one out of three air tower gauges was

wrong by 4 psi (28 kPa) or more, and three out

of five were wrong by 2 psi (14 kPa) or more. Pocket gauges were more accurate. Only one in ten was found to be wrong by 2 psi (14 kPa) or more. There is the further complication that the

trip to the service station warms up the tires, thereby temporarily increasing their pressure by an unknown amount. This may be negligible or may exceed 6 psi (41 kPa), depending on cir- cumstances. To get a correct measurement, one must check the pressure after the tires have had time to cool for three hours or longer

after a trip. One must never deflate or "bleed" a

hot tire down to the recommended pressure. To

do so could leave the tire seriously underinflated. Figure 16 shows tires in various states of in- flation.

25
Tire Rotation

To equalize tread wear, tires should be rotated

in accordance with the recommendation in the

Car Owner's Manual, if available, or at 6000-

8000 mi (10,000-13,000 km) intervals. However,

if irregular wear begins to develop, the causes

should be corrected and the tires rotated before

the recommended mileage interval.

BIAS AND BELTED BIAS TIRES

4 TIRE 5 TIRE

LR I I RR LR I /I RR

RADIAL TIRES

4 TIRE 5TIRE

LF H I ''''I I

LR I I RR LR I //^l F)F!

SPARE

SIMOW TIRES

STORAGE

TO INSTALL TO REMOVE

FIGURE 17. TIRE ROTATION [4]

26

As shown in figure 17, the rotation pattern for bias and bias-belted tires is different from that

,

for radial-ply tires.

Because of change in the tire-wheel-brake

assembly during normal service or due to

rotation, rebalancing may be required.

Detection of Faults and Impending Troubles

A visual inspection should be performed during

the daily inflation pressure check in order to determine the condition of the tires, valves, and

wheels. Missing valve caps should be replaced.

The following conditions are signs of trouble:

• Tread or sidewall cuts, cracks, or snags deep enough to expose tire ply

cords.

• Bulges or knots, indicating possible

separation of tread or sidewall from j tire body.

• Front tire wear different from the rear. | • Uneven wear across the tread of any

tire.

• Left front and right front tire wear

j unequal. j

• Left rear and right rear tire wear

unequal.

• Cupping, flat spotting, etc. i

• Front tire tread having scuffed appear- f ance, with feathered edges on one i side of tread ribs or blocks. ]

i There are other types of tire damage that are - internal and not evident unless the tire is re- ^ moved from the rim.

Mixing and Matching Tires

Tests conducted by the Calspan Corporation for the National Highway Traffic Safety Administration on the influence of tire properties on car handling characteristics show that mixing

different types and sizes of tires on the front and rear wheels can make some cars less stable in severe maneuvers that might be

experienced in accident avoidance situations. Tires performed best when fitted in complete |
The uneven tread wear patterns shown below were caused by wrong inflation pressure, misalignment, improper balance or

suspension neglect. These conditions can be avoided or

corrected.

WEAR WEAR WEAR MAXI U M SCU F F AR E A

HEAVY WEAR + WEAR+ ERRATIC

DEPRESSIONS i SCUFFUFF WEAR CUPPING Y

Abnormal Tread Wear

As mentioned earlier the mechanical condition

of the car and the tire inflation pressure play sig- nificant roles in tire tread mileage. The causes

of abnormal tread wear should be corrected as soon as they are discovered. Figure 18

illustrates some of the uneven tread wear

patterns which may be encountered.

A tire should be replaced if it wears unevenly so

that two or more adjacent grooves of the tread are less than 1/16 in (1.6 mm) thick. Tires made

since 1968 have built-in wear indicators which

appear as smooth narrow "wear bars" across

the tread when the tread depth gets down to

this level (see fig. 19).

Repairs and Servicing

If a tire loses all or most of its air pressure, particularly at high speed, and is run even a short

distance while flat, it should be considered

unsuitable for high speed use, since the extent

of the damage is not always easy to determine.

The damaged tire should be repaired, if possible, and used on a vehicle in other than

pursuit or emergency service.

FIGURE 18. UNEVEN TREAD WEAR

sets. Different constructions (bias, bias-belted,

ii and radial) should never be mixed on the same

|i axle. The same applies for different sizes.

! Appendix C gives a summary of the rules on

mixing as recommended by the Rubber Manufacturers Association.

!|

Positioning of Least Worn Tires

The available accident data suggest that tires having similar amounts of tread wear be placed

j on the same axle, with the least-worn tires

! installed on the rear of the car. When putting

I two new tires on a vehicle mount them on the

j rear wheels. This will provide better traction,

1 handling, and blowout protection. If only a

single new tire is being installed, pair it with the

j best remaining tire and place them on the rear

axle. FIGURE 19. WEAR BARS

27
lACP Postscript

At the request of the Law Enforcement Standards Laboratory (LESL), this tire guide was

reviewed by the International Association of Chiefs of Police, National Advisory Committee for Law Enforcement Equipment and Technology (NACLEET). While the guide is excellent for the

most part, NACLEET felt that certain important information concerning the use of the guide

should be brought to the attention of the law enforcement user.

• The guide contains the results of tests conducted to evaluate the comparative traction

performance of various brands and sizes of high speed pursuit tires. Although the pro- cedures used in the tests were methods developed and standardized by the American

Society for Testing and Materials (ASTM) for standard passenger vehicle tires, NACLEET believes that the use of 6-inch rims and an inflation pressure of 24 psi are

not representative of police usage and might have produced results and rankings

which are inapplicable. Most police patrol cars are equipped with 6.5-inch or 7-inch

rims and use the manufacturer's recommended inflation pressure of 30 or 32 psi.

Therefore, NACLEET has recommended that future tests of pursuit tires be conducted

with cars equipped with the wider rims and with tires inflated to the higher pressures.

• Not all manufacturers submitted tires for high speed testing by the General Services

Administration (GSA). Therefore, the omission of a particular brand or size of tire from

the GSA Qualified Products List (Appendix B) does not necessarily mean that the tire

is unacceptable for police use. Conversely, the inclusion of a particular brand or size

of tire on the List should not be considered a guarantee of satisfactory future perfor- mance. NACLEET strongly concurs with the LESL recommendation that whenever

high speed performance is required, departments should always procure tires which

have been certified by the manufacturer for high speed pursuit—usually 125 mph.

• The recommendations contained in the guide for tire maintenance and inspection

should be followed unless they conflict with a manufacturer's recommendation. In that case, the manufacturer's recommendation should take precedence. Well maintained

and inspected tires will lessen the risk of high speed tire failure and reduce injuries

and property damage.

Colonel James C. Crawford, Chief

Minnesota State Patrol Chairman, NACLEET/ 1 ACP

Assistant Chief Louis L. Sporrer

Los Angeles Police Department

Chairman, Transportation Subcommittee, NACLEET/IACP

28
REFERENCES

Brenner, F. C, "Tires, Their Selection and Care,"

NBS Consumer Information Series, NBS CIS 2, National Bureau of Standards, Washington, D.C. 20234, November 1 970. "Care and Service of Automobile Tires," Rubber

Manufacturers Assoc., 444 Madison Ave., New

York, N.Y. 10022.

Collard, Jared J., "Report on an Investigation of the High Speed Hazards of Steel Belted Radial

Tires on Police Patrol Cars," NBS Special Publi- cation 480-18, National Bureau of Standards,

Washington, D.C. 20234, June 1977. "Consumer Tire Guide," Tire Industry Safety

Council, National Press Building, Washington,

D.C. 20004.

Neill, A. H., Jr., and Hinch, J. A., "Selection

Guide for High Speed Police Pursuit Tires

(Traction)," NHTSA Technical Note T-1020, National Highway Traffic Safety Administration,

Washington, D.C. 20590, September 1 976. "Passenger Tire Manual," B. F. Goodrich Tire

Co., 500 Main Street, Akron, Ohio 44318.

7. "Radial Auto Tire Service Manual," Goodyear

Tire and Rubber Co., 1144 E. Market St., Akron,

Ohio 44316.

8. "Radial Pursuit Tire Maintenance Procedures,"

Firestone Tire and Rubber Co., 1200 Firestone

Parkway, Akron, Ohio 44317.

9. "Radial Tire Chain Test," United States Auto

Club, 4910 West 16 St., Speedway, Indiana

46224, April 1975.

10. "Radial Tire Service Manual," B. F. Goodrich

Tire Co., 500 Main St., Akron, Ohio 44318.

11. "Rolling Resistance of Tires Measured Under

Transient and Equilibrium Conditions on Calspan

Research Facility," DOT-TSC-OST-76-9, U.S. De- partment of Transportation, Washington, D.C. 20590, March 1976.

12. "Tire Application Guide for Passenger Cars,"

Rubber Manufacturers Assoc., 444 Madison

Ave., New York, N.Y. 10022.

29

APPENDIX A

Appendix A—Tire Interchangeability and Load and Inflation Data |4|

Tire size or designation

Load limits (pounds per tire)

Load Range B (4-ply rating) ^

Load Range C (6-ply rating) Load Range D (8-ply rating)

Bias and belted bias ply Radial ply Cold inflation pressures—pounds per square inch

Former

desig- nation 78 series 70 series Metric 78 series 70 series 20 22 24 26 28 30 32 34 36 38 40

D78-14 D70-14 DR78-14 DR70-14 1010 1070 1120 1170 1220 1270 1320 1360 1410 1450 1490

7.35-14

E78-14 E70-14 185R14

ER78-14 ER70-14

1040 1100 1160 1210 1260 1310 1360 1040 1100 1160 1210 1260 1310 1360 1070 1130 1190 1240 1300 1350 14001400 1450

1410 1450

1440 1490

1 490 1 540

1500 1540

1 540 1 580

7.75-14

F78-14 F70-14 195R14FR78-14 FR70-14

1150 1210 1270 1330 1390 1440 1500

1150 1210 1270 1330 1390 1440 1500

1160 1220 1280 1340 1400 1450 1500

1550 1600

1 540 1 590

1550 1610

1650 1690 1640 1690 1650 1700

8.25-14

G78-14 G70-14 205R14

GR78-14 GR70-14

1250 1310 1380 1440 1500 1560 1620

1250 1310 1380 1440 1500 1560 1620

1250 1310 1380 1440 1500 1560 1620

1670 1730

1680 1730

1680 1730

1780 1830

1780 1830

1780 1830

8.55-14

H78-14 H70-14 215R14

HR78-14 HR70-14

1360 1430 1510 1580 1640 1710 1770

1360 1430 1510 1580 1640 1710 1770

1360 1440 1510 1580 1650 1710 1770

1830 1890

1830 1890

1830 1890

1950 2000

1950 2010

1950 2010

8.85-14 J78-14 J70-14 JR78-14 JR70-14 225R14

1430 1510 1580 1660 1730 1790 1860

1430 1500 1580 1650 1720 1790 1860 1430 1510 1580 1660 1730 1790 1860

1920 1990

1920 1980

1920 1980

2050 2100 2040 2100

2040 2100

L70-14 LR70-14 1520 1600 1680 1750 1830 1900 1970 2040 2100 2170 2230

7.35-15 E78-15 E70-15 ER78-15 ER70-15 185R151070 1130 1180 1240 1290 1340 1390

1070 1130 1190 1240 1300 1350 1400

1070 1130 1180 1240 1290 1340 1390

1440 1480

1440 1490

1430 1480

1 530 1 570

1540 1580

1520 1570

7.75-15 F78-15 F70-15 195R15

FR78-15 FR70-15

1150 1210 1270 1330 1380 1440 1490

1160 1220 1280 1340 1400 1450 1500

1540 1590

1550 1610

1640 1690

1650 1700

8.15-15 G78-15 670-15

8.25-15

205R15

GR78-15 GR70-15

1240 1300 1370 1430 1490 1550 1610

1250 1310 1380 1440 1500 1560 1620

1250 1310 1380 1440 1500 1560 1620

1660 1720

1680 1730

1670 1730

1770 1820

1780 1830

1780 1830

8.45-15

H78-15 H70-15

8.55-15

215R15

HR78-15 HR70-15

1340 1410 1480 1550 1620 1680 1740

1340 1410 1460 1550 1620 1680 1740

1360 1440 1510 1580 1650 1710 1770

1360 1430 1510 1580 1640 1710 1770

1800 1860 1800 1860

1830 1890

1830 1890

1920 1970

1910 1970

1950 2010

1950 2000

8.85-15 J78-15 J70-15 225R15

JR78-15 JR70-15

1430 1510 1580 1650 1720 1790 1860 1430 1500 1580 1650 1720 1790 18601920 1980

1920 1980 2040 2100

2040 2100

9.15-15

L78-15 L70-15 235R15LR78-15 LR70-15

1510 1600 1680 1750 1830 1900 1970

1510 1600 1680 1750 1830 1900 1970

1520 1600 1680 1750 1830 1900 1970

2030 2100 2040 2100

2040 2100

2160 2230

2170 2230

2170 2230

31
APPENDIX B

FEDERAL QUALIFIED PRODUCTS LIST Le i, 1978 SUPER SED IMG QPL-ZZ-T-38IM-2 "r April 22, 1976, and QPL-ZZ-T-38IM-I

PRODUCTS QUALIFIED UNDER FEDERAL SPECIFICATIOH

"'"^

ZZ-T-38U'

FSC 2610

TIRES, PNEUMATIC, VEHICULAR (HIGHWAY)

This Qualified Products List has been prepared by the General Services Administration for passenger car tires. Group lA; light truck tires. Groups 2 and 2A; and truck-bus tires. Groups 3 and 3A; which have been approved

for procurement by the Federal Government. The list is based upon the results of road tests prescribed in Federal Specification ZZ-T-381M. This list is subject to change without notice; revision or amendment will

be issued as necessary. The inclusion of tires in this list does not release the supplier from compliance with

the specification requirements for tires supplied to the Government. Use of this Qualified Products List for advertising in such a manner as to state or imply that tires listed herein are endorsed or preferred by the Federal Government or are considered by the Government to be superior to other tires is prohibited.

The activity responsible for this Qualified Products List is the General Services Administration, Federal

Supply Service, Washington, D.C. 20l406.

NOTE: 1. SINCE ALL TIRES MANUFACTURED WERE NOT OFFERED FOR TESTING, THE OMISSION OF ANY TIRE FROM THIS QPL DOES NOT NECESSARILY MEAN THAT THE UBLISTED TIRE IS EITHER UNSAFE 0? INFERIOR IN QUALITY.

2. ALL SIZES AND PLY RATINGS FOR TIRE BRANDS SHOWN IN THIS QPL ARE ACCEPTABLE (SEE FEDERAL STANDARD

NOS. 316 AND NO. 3I+5. )

GOVERNMENT DESIGNATION

AND

ITEM NUMBER

SUPPLIER '

"BRAND NAME"

TEST OR QUALIFICATION REFERENCE

SUPPLIER '

NAME AND ADDRESS

Passenger Pursuit and Emergency High

Group lA-Passenger Car (Tubeless

Item No. I.P.D.IA.1.1

Group lA-Passenger Car

(Tubeless

Item No. I.P.D.IA.1.2

Group lA-Passenger Car

(Tubeless

Item No. I.P.D.IA.11.1

Construct

Speed 78 Series, Bias Ply, Ti.beless ion Tires

"SUPER HPG," tubeless,

nylon, 14/1*, regular tread, black and white wall, high

speed, highway service

"SUPER HPG," tubeless,

nylon, 6/6, regular tread, black and white wall, high

speed, highway service

"POLICE SPECIAL," tubeless,

nylon, k/h, regular tread,

in black wall only, high

speed, highway service.

FMA-l-22363-73

FMJl-ll-22363-73

Armstrong Rubber Company

500 Sargent Drive New Haven, CT O6507

Code Plant

CV Natchez, MO

CE West Haven, CT

CV Natchez, MO

CE West Haven, CT

Goodyear Tire 4 Rubber Co. Akron, OH 1*1*316

Code Plant

MB Akron II, OH

32
FEDERAL QUALIFIED PRODUCTS LIST CONTINUATION SHEET

GOVERNMENT DESIGNATION

AND

ITEM NUMBER

SUPPLIER'S

"BRAND NAME"

TEST OR QUALIFICATION

REFERENCE SUPPLIER'SNAME AND ADDRESS

Passenger Pursuit and Emergency Hiql Construction TiresSpeed 78 Series, Bias Ply, Tubeless

Con't. FMA-11- 22363-73 Goodyear Tire & Rubber Co. Akron, OH 44316

Group lA-Passenger Car

(Tubeless

Item No. I.P.D.IA.11.2

"WINGFOOT SPECIAL," tubeless, nylon, '^/'^i, regular

tread, in black and white

wall, high speed, highway

MB Akron II, OH

Group lA-Passenger Car

(Tubeless)

Item No. I.P.D.IA.11.3

Group lA-Passenger Car

(Tubeless) Item No. I.P.D.IA.11.4

service.

"POLICE SPECIAL SUBURBANITE XG78 , " tubeless

nylon, 4/4, mud/snow tread, black wall only, high speed

highway service.

"WINGFOOT SPECIAL

SUBURBANITE XG78 , " tubeless

nylon , 4/4 , mud/snow tread

black and white wall, high

speed, highway service.

Akron II, OH

Akron II, OH

Passenger:

Group lA-Passenger Car

(Tubeless) Item No. I.P.B.IA.11.1

Group lA-Passenger Car

(Tubeless) Item No. I.P.B.IA.11.2

Group lA-Passenger Car

(Tubeless)

Item No. I.P.B.IA.11.3

Group lA-Passenger Car

(Tubeless)

Item No. I.P.B.IA.11.4

Pursuit and Emergency High Speed 78 Series, Bias-belted,

Tubeless Consltruction Tires

"POLICE SPECIAL POLYGLAS ,

tubeless, poly/glass,

4+2/4, regular tread, in black wall only, high speed,

highway service.

"WINGFOOT SPECIAL POLYGLAS,' tubeless, poly/glass,

4+2/4, regular tread, in black and white wall , high

speed, highway service.

"POLICE SPECIAL SUBURBANITE

POLYGLAS," tubeless, poly/

glass, 4+2/4, mud/snow

tread, in black wall only,

high speed , highway service

"WINGFOOT SPECIAL SUBURBANITE POLYGLAS," tubeless,

poly/glass, 4+2/4, mud/snow

tread , in black and white

wall, high speed, highway

service.

FMA-11-22363-73 Goodyear Tire & Rubber Co. Akron, OH 44316

Code Plant

MJ Topeka, KS

MJ Topeka, KS

MJ Topeka, KS

MJ Topeka, KS

33
FEDERAL QUALIFIED PRODUCTS LIST CONTINUATION SHEET

GOVERNMENT DESIGNATION

AND ITEM NUMBER SUPPLIER'S

"BRAND NAME"

TEST OR QUALIFICATION

REFERENCE SUPPLIER'SNAME AND ADDRESS

Passeng(!r: Pursuit and Emergency Hi ;h Speed 78 Series, Radial Pl-^ -belted Tubeless Cons iruction Tires

Group lA-Passenger Car

(Tubeless)

Item No. I.P.R.IA.5.1

Group lA-Passenger Car

(Tubeless)

Item No. I.P.R.IA.5.2

Group lA-Passenger Car

(Tubeless) Item No. I.P.R.IA.6.1

Group lA-Passenger

(Tubeless) Item No. I.P.R.IA.6.2

Group lA-Passenger Car

(Tubeless) Item No. I.P.R.IA.11.1

Group lA-Passenger Car

(Tubeless

Item No. I.P.R.IA.11.2

Group lA-Passenger Car

(Tubeless)

Item No. I.P.R.IA.11.3

Group lA-Passenger Car

(Tubeless) Item No. I.P.R.IA.11.4

"ELITE R.S. PATROL RADIAL,"

tubeless, polY/aramid/nylon

2+2+2/4, regular tread, in black wall only, high speed

highway service.

"CW-R44 R.S. PATROL RADIAL,' tubeless, poly/aramid/nylon

2+2+2/4, mud/snow tread, in black wall only, high speed

highway service

"SUPER 125 RADIAL," tubeless, poly/aramid , 2+2/4,

regular tread, in black wall only, high speed,

highway service.

"TOWN AND COUNTRY SUPER

flADIAL," tubeless, polyester/aramid , traction tread

(mud/snow) , highway and off-the-road service.

"POLICE SPECIAL RADIAL,"

tube less , poly/rayon

2+4/4, regular tread, black wall only, high

speed, highway service.

"WINGFOOT SPECIAL RADIAL,"

tubeless , poly/rayon

2+4/4, regular tread, black and white wall, high

speed , highway service

"POLICE SPECIAL SUBURBANITE

RADIAL," tubeless, poly/

rayon, 2+4/4, mud/snow

tread, black wall only,

high speed , highway service

"WINGFOOT SPECIAL SUBURBANITE RADIAL," tubeless,

poly/rayon, 2+4/4, mud/snow

tread, black wall only,

high speed, highway service

FMA-5-22363-73

FMA-6-22363-73

FMA-11-22363-73

Dunlop Tire & Rubber Co. Box 1109 Buffalo, NY 14240

Code Plant

DB Huntsville, AL

Huntsville, AL

Firestone Tire & Rubber Co. Akron, OH 44317

Code Plant

VC Albany, GA

Albany , GA

Goodyear Tire & Rubber Co. Akron, OH 44316

Code Plant

MK Union City, TN

MK Union City, TN

MK Union City , TN

MK Union City, TN

34
FEDERAL QUALIFIED PRODUCTS LIST CONTINUATION SHEET

GOVERNMENT DESIGNATION

AND

ITEM NUMBER SUPPLIER'S

"BRAND NAME"

TEST OR QUALIFICATION

REFERENCE SUPPLIER'S

NAME AND ADDRESS

Con't. Passenger: Pursuit and Emergency High Speed 78 Series, dial

Group lA-Passenger Car

(Tubeless) Item No. I.P.R.IA.11.5

Group lA-Passenger Car

(Tubeless

Item No. I.P.R.IA.11.6

Group lA-Passenger Car

(Tubeless) Item No. I.P.R.IA.11.7

Group lA-Passenger Car

(Tubele: Item No. I.P.R.IA.11.8

Group lA-Passenger Car

(Tubeless) Item No. I.P.R.IA.23.1

Group lA-Passenger Car

(Tubeless) Item No. I.P.R.IA.4.1

Group lA-Passenger Car

(Tubeless) Item No. I.P.R.IA.11.9

Ply-belted, Tubeles Construction Tires

Con't FMA-ll-22363-73

"POLICE SPECIAL RADIAL

FLEXTEN," tubeless,

poly/aramid , 2+4/4, regular

tread, black wall only,

high speed, highway service

"CUSTOM H.F. RADIAL FLEXTEN," tubeless, poly/ aramid , 2+4/4, regular

tread, black and white wall

high speed , highway service

"F32 ALL WINTER RADIAL FLEXTEN," tubeless, poly/aramid

2+2/4, mud/snow tread, black and white v;all, high

speed, highway service.

F32 ALL WINTER RADIAL FLEX

TEN," tubeless, poly/aramid,

2+2/5, mud/snow tread, black

and white wall, high speed,

highway service

Goodyear Tire 8c Rubber Co. Akron, OH I*lt3l6 MM Fayetteville, NC

Fayetteville , NC

MK

MK

Union City, TN

Uniort City, TN

FMA-23-22363-73

"CN-75 CENTURINO," tubeless, rayon/steel/nylon

2+2+2/4, regular tread, black and white wall, high

speed , highway servi ce

Paiisenger: Pursuit and Emergen zy High Speed 70 Series , Radi Ply-belted, Tubeles ; Construction Tires

'HSP-a25," tubeless, poly/

aramid 2+2/4, regular

tread, in black wall only,

high speed , highway service,

"POLICE SPECIAL RADIAL,"

tubeless , poly/rayon

2+4/4 , regular tread , black wall only, high

speed , highway service

FMA-4-22363-73

FMA-ll-22363-73

Pirelli Tire

600 3rd Avenue

New York, NY 10016

Code Plant

Settimo-Torino, Italy

Dayton Tire & Rubber Co.

P.O. Box 1026 Dayton, OH 45401

Code Plant

HY Oklahoma City, OK

Goodyear Tire & Rubber Co. Akron, OH 44316

Code Plant

MK Union City, TN

35
FEDERAL QUALIFIED PRODUCTS LIST CONTINUATION SHEET

GOVERNMENT DESIGNATION

AND

ITEM NUMBEP SUPPLIER '

"BRAND NAME"

TEST OR QUALIFICATION

REFERENCE

SUPPLIER '

NAME AND ADDRESS

Con't FMA-11-22363-73 jOodyecLT Tire h. Ruober Co. Akron, CH 44315

Group lA-Passenger Car

(Tubeless) Item No. I.P.R.IA.11.10

"WINGFOOT SPECIAL RADIAL,"

tubeless, poly/rayon

2+4/4, regular tread, blade

and white wall, high speed,

highway service.

MK Union City, TN

Group lA-Passenger Car

(Tubeless) Item No. I.P.R.IA.11.11

"POLICE SPECIAL SUBURBANITE

RADIAL," tubeless, poly/ rayon 2+4/4, mud/snow tread, black wall only, high speed, highway service.

MK Union City, TN

Group lA—Passencfer Car

(Tubeless) Item No. 1.P.R,1A.11.12

"WINGFOOT SPECIAL SUBURBANITE RADIAL," tubeless,

poly/rayon 2+2/4 , mud/snow

tread , outlined white

letters , high speed , high- way service

MK Union CityTN

Group lA-Passenger Car

(Tubeless) Item No. I.P.R.IA.11.13

"POLICE SPECIAL RADIAL FLEX- TEN," tubeless, poly/aramid

2+4/4, regular tread, high

speed, highway service.

MK Union City, TN

Group lA-Passenger Car

(Tubeless)

Item No. I.P.R.IA.11.14

"CUSTOM H.P. RADIAL FLEXTEN," tubeless, poly/aramid

2+4/4, regular tread, black

and white wall, hiah speed,

highway service.

MK Union City, TN

Group lA-Passenger Car

(Tubeless) Item No. I.P.R.IA.11.15

"CUSTOMARD GT RADIAL

FLEXTEN," tubeless, poly/ aramid 2+4/4, regular

tread, black and white wall

high speed , highway service

MK

Code

Union City

Plant

TN ^

Group lA—Passenger C&r (Tubeless

Item No. 1. P. E. LA. 11. 16 FLEXTEN," tubeless, poly/

aramid 2+2/U, mud/snow

tread, black eind white

wall, high speed, highway

service

MK Union City, TN

Group lA-Passenger Car (Tubeless

Item No. I.P.R.IA.11.17

"F32 ALL WINTER RADIAL

FLEXTEN," tubeless, poly/

aramid 2+2/6, mud/snow

tread, black and white

wall, high speed, highway

service.

MK Union City, TN

36
APPENDIX C

og

I O

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(DQ.

Q. <

n

•ac

0)E

Eoo

c

5oD

T3

(0

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