INVESTIGATION OF TIRE WEAR

THE PURPOSE IS TO DETERMINE THE RELATIVE EFFECT OF VARIOUS STANDARD TYPES OF ROAD SURFACES UPON THE WEAR OF AUTOMOBILE TIRES. BOTH LABORATORY AND ROAD TESTS WERE MADE. GENERAL CONCLUSIONS DRAWN ARE AS FOLLOWS: (1) THE DIFFERENCE IN THE EFFECTS OF CERTAIN HIGH TYPE PAVEMENTS SUCH AS CONCRETE AND BRICK, AND PROBABLY ASPHALT, UPON TIRE WEAR IS NOT GREAT IF THESE PAVEMENTS ARE IN HIGH-CLASS SURFACE CONDITION, (2) ROUGHNESS OF LONGITUDINAL CONTOUR CAUSING BOUNDING, ACCELERATION, IMPACT, AND DECELERATION, WITH ITS ACCOMPANYING SLIPPAGE HAS A MARKED EFFECT UPON THE WEAR OF TIRES RUNNING WITH STANDARD INFLATION, (3) UNDER-INFLATION IS PROBABLY THE CAUSE OF MUCH GREATER WEAR THAN IS ORDINARILY ASSIGNED TO IT, ALTHOUGH IT CANNOT BE SAID HOW MUCH THIS EFFECT IS OFFSET BY DECREASED WEAR DUE TO THE LESSENED AMOUNT OF BOUNDING AND IMPACT, (4) A VAST AMOUNT OF TIRE WEAR RESULTS FROM VARIOUS CAUSES NOT ASSIGNABLE TO PAVEMENT TYPE. AND IF A GREAT AMOUNT OF VALUE IN TIRES IS DISSIPATED IN OTHER WAYS THAN IN RUNNING, PROPERLY CONTROLLED, OVER WELL MADE SURFACES, THEN CARE SHOULD BE TAKEN NOT TO OVERESTIMATE THESE VALUES IN THE SOLUTION OF PROBLEMS IN HIGHWAY ECONOMICS UNTIL MORE DATA IS AVAILABLE, AND (5) TIRE WEAR INVESTIGATION, USING LABORATORY METHODS AND SMALL-SCALE DEVICES INSTEAD OF STANDARD EQUIPMENT MAY GIVE RESULTS WHOLLY MISLEADING. RELATIVE VALUES MAY BE OBTAINED, BUT SHOULD BE USED WITH CAUTION UNTIL MORE IS KNOWN ABOUT THE RELATION BETWEEN THE AMOUNT OF VALUE ACTUALLY EXISTING IN TIRES AND THAT USED IN OTHER WAYS OTHER THAN BY RUNNING PROPERLY OVER FIRST-CLASS PAVEMENTS SUCH AS BY STOPPING AND STARTING, BY PHYSICAL DETERIORATION WHILE STANDING, RUNNING OVER ROUGH PAVEMENTS AND ABUSES SUCH AS UNDER-INFLATION AND HIGH SPEEDS.