Abstract:
An improved non-skid tread configuration for vehicle tires. The tread design including a plurality of suction means spaced-apart in all directions around the circumference of the tread portion of the tire for providing improved resistance in all directions to skidding on ice or snow.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention relates to pneumatic tires, and more particularly, to an improved tire for use on ice or snow covered roadways. 
     As the tread portion of a pneumatic tire travels through the footprint with the roadway, many different forces are experienced. Under normal dry road conditions, the principal lateral force experienced by the tread portion of the tire is the longitudinal force parallel to the direction of travel of the tire. The lateral force experienced by the tread portion under dry road conditions is generally so small when compared to the longitudinal force to be of any major consequence. However, ice and snow covered roadways present a substantially reduced coefficient of friction between themselves and the tread portion of the tire. As a result, lateral stability of the tread portion of the tire is of increased importance. 
     To obtain the increased lateral stability necessary to operate a motor vehicle on an ice or snow covered roadway, various non-skid devices using hardened metals have been devised. These include tire chains and studs inserted into the tread portion of a tire. The tire chains are inconvenient since one must stop the vehicle and install the chains on the driven wheels when necessary. This is time consuming and must be done in freezing weather conditions beside the roadway. In addition, the use of chains forces the driver to proceed at a slower speed than he might otherwise be able to travel due to the uncomfortable ride chain equipped tires provide. Another undesirable feature of tire chains is their potential to damage the body of the vehicle on which they are mounted if they break while traveling. 
     Tire chain or stud equipped tires when used on roadway surfaces that are clear of ice and snow present several undesirable side-effects. Not only are they noisier than tires not so equipped, they also cause physical damage to the surface of the roadway when the hardened metal strikes it. Small pieces of the roadway are broken free by such impact which not only increase the maintenance costs of the roadway but also presents dust pollution which is an increasingly serious social and environmental problem. 
     To overcome these problems, it is desirable to have a tire with a tread design which offers a non-skid footprint pattern which is resistant to forces in all directions without the use of hardened metal devices. The present invention provides such a tread design. 
     In accordance with the illustrated embodiments, the present invention provides a pneumatic ice and snow tire for a vehicle having a tread that includes a roadway bearing surface having defined therein a plurality of spaced-apart means for establishing suction between the tread and ice and snow on a roadway. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic fragmentary plan view of an outer peripheral surface of one embodiment of the non-skid tire of the present invention. 
     FIG. 2 in a cross-sectional view of the tire tread portion of the tire surface shown in FIG. 1 taken along line II--II. 
     FIG. 3 is a cross-sectional view of a tire tread portion of a tire incorporating an alternate embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The tread configuration of both embodiments of the present invention is characterized primarily in that the radially outwardly located peripheral roadway bearing surface of the tire includes two linear arrays of suction members which may be produced by any of a number of well-known tire molding techniques for tires of several contruction styles. 
     Referring to FIGS. 1 and 2, there is shown a first embodiment of tread design of the present invention. In FIG. 1, the footprint 10 of this tread design is illustrated with the outer surface 4 of the tread incorporating a plurality of spaced-apart circular or annular cavities or grooves 1. Each of grooves 1 set off and surround an island 2 from the tread surface 4 with each island 2 having a concave suction member 3. 
     In FIG. 2, the cross-section of the tread design of FIG. 1 reveals several other of the features of this design. Thus, each cavity or groove 1 includes an outer annular wall extending radially inwardly of the tire from the roadway surface, which merges into an annular bottom wall of the cavity. Each island 2 includes a radially outwardly extending pedestal portion 5 to space the rear wall of the suction member 3, mounted thereon, away from the bottom wall of groove 1. In addition, each of pedestals 5 have a smaller cross-sectional area than the surface area of suction member 3, when viewed perpendicularly to the outer surface 4 as in FIG. 1, to allow more flexibility in the outer rim of suction member 3. Further, suction member 3, is concave with its center area extending toward the inside of the tire away from outer surface 4 with its outer rim even with or slightly recessed from outer surface 4 and in spaced relation to said annular cavity wall. Groove 1 is also shown in FIG. 2 as being substantially &#34;L&#34; shaped and surrounding island 2. 
     By recessing at least the center area of suction member 3 from the outer surface 4 of the tire, the load weight and wear presented to suction member 3 is reduced. This provides for longer tire wear by extending the life of suction members 3 and their ability to seal with and hold to ice and snow. By recessing suction members 3, they will not wear unnecessarily when the roadway is free of ice and snow. 
     The alternate embodiment of the present invention as shown in FIG. 3 includes a tread portion of a tire having an outer surface 4&#39; with concave suction members 3&#39; moulded therein. This configuration operates similarly to that of the first embodiment. 
     From the foregoing description, it will be apparent that the invention disclosed herein provides a tire with a novel non-skid tread pattern for use on ice and snow. As will be understood by those familiar with the art, the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. By way of example, one could substitute any polygonal shape for the circular suction members 3 or pedestals 5.