Abstract:
This invention pertains to a newly manufactured airless or pneumatic tire having a rubber structure and a polyurethane tread.

Description:
BACKGROUND 
       [0001]    The field of this invention is tires which have been made entirely of rubber for about one hundred years. Most pneumatic tires are made from a combination of natural rubber and synthetic rubber. Rubber has been the only material capable of holding inflation pressure in a flexible air container, carrying a load and remaining durable in a difficult operating environment. Today&#39;s tire is longer wearing, more tractive, tougher to puncture and much safer than its predecessors and the cost per mile is significantly less than it was in the past. 
         [0002]    The tire market is very competitive and tires are purchased based on performance versus price. Tread wear, traction, durability, comfortable ride. 
         [0003]    and fuel economy are the most important performance parameters in the market place. 
         [0004]    Carbon black is added to tires to improve tread wear and reduce cost. It causes all tires to have black treads which can put black marks on pavement and driveways if any slippage occurs. This is a problem for tread wear causes all rubber treads to have a black color. 
         [0005]    Rubber is inherently hysteretic, absorbing energy and causing a rubber treaded tire to heat up during service adversely affecting durability and increasing rolling resistance which reduces vehicle fuel economy. Pneumatic rubber treaded tires are expanded into vulcanizing molds using high internal pressure. When these tires are removed from the mold and inflated to a significantly lower pressure for service, they are significantly less round than their tread mold causing a less comfortable vehicle ride. Rubber treaded tires also exhibit internal stresses adversely affecting durability and caused by expansion of the tire into the tread portion of the mold. 
       SUMMARY OF INVENTION 
       [0006]    The newly manufactured tire of this invention includes a vulcanized rubber structure which can utilize reinforcing textiles and wires to contain internal inflation pressure and control dimensions and shape of the finished tire. 
         [0007]    The tire of this invention also includes a polyurethane tread. Polyurethane is less hysteretic than rubber which causes a polyurethane treaded tire to run cooler than a rubber treaded tire enhancing durability in service. Also the lower hysteresis of polyurethane lowers rolling resistance and improves fuel economy of polyurethane treaded tires relative to rubber treaded tires. 
         [0008]    Polyurethane can be formulated to have significantly more abrasion resistance than rubber improving tread wear over rubber treaded tires. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0009]      FIG. 1  shows a cross section and  FIG. 2  shows an isometric view of the pneumatic tire  10  having a reinforced rubber structure  12  and a polyurethane tread  14 . 
       
    
    
       [0010]    The vulcanized rubber structure  12  in  FIG. 1  is reinforced by at least two beads  16  and at least one ply  18  and at least one belt  22 . Additional components shown in  FIGS. 1 and 2  are: innerliner  20  and sidewalls  24 . 
         [0011]    The tire  10  shown in  FIGS. 1 and 2  is a very elementary passenger tire; however, all sizes and types of tires are included in this patent. 
       DETAILED DESCRIPTION 
       [0012]    The tire of this invention includes a vulcanized rubber structure utilizing reinforcing plies, belts, beads and other rubber components to contain internal inflation pressure and to control dimensions and shape of the finished tire. 
         [0013]    The tire of this invention also includes a polyurethane tread which can be spliceless or have a tread splice. Most rubber treaded tires have a tread splice which can cause ride and durability problems in service. Polyurethane can be formulated to be any desired color without a performance penalty but rubber can only be black if it is formulated to be durable enough for a tire tread. 
         [0014]    Polyurethane can be formulated to not mark pavement as all rubber treaded tires do. This is a particular advantage for landscapers and building contractors whose vehicles with rubber treaded tires mark concrete driveways requiring labor to remove the unsightly black rubber tread marks. 
         [0015]    Rubber treaded pneumatic tires are expanded or stretched into their vulcanizing mold using high internal inflation pressure. When a rubber tire is subsequently inflated for service to a much lower pressure, it&#39;s roundness and shape are controlled by it&#39;s reinforcement geometry and it cannot be as round as the mold in which is was vulcanized. The polyurethane treaded tire of this invention can be as round, when inflated for service, as the tread mold which produced it because the vulcanized reinforced rubber structure is inflated to the same internal pressure inside the tread mold as it is in service. In service the roundness and tread shape will be the same as the mold delivering a smoother ride and better tread wear and traction than is possible with a rubber treaded tire. 
         [0016]    Because the vulcanized reinforced rubber structure is inflated to operating pressure inside its tread mold and liquid polyurethane fills the space between the inflated rubber structure and the tread mold and the liquid polyurethane subsequently solidifies while in the mold, detrimental internal stresses inside this tire will be significantly less than in a rubber treaded tire. 
         [0017]    The vulcanized reinforced rubber structure can have a texturized surface in the area where the polyurethane tread will be applied to promote adhesion to the polyurethane tread in service. The desired texturizing is built into the vulcanizing mold.