NEW TIRE-STUD DEVELOPMENTS

Abstract

ALTHOUGH THEY OFFER SNOWBELT MOTORISTS SUBSTANTIAL IMPROVEMENT OF VEHICLE CONTROL ON ICY ROADS, STUDDED TIRES HAVE BEEN ATTACKED WITH INCREASING VIGOR BY HIGHWAY OFFICIALS FOR THEIR CONTRIBUTION TO ROAD WEAR. TESTS OF SOME RECENTLY DEVELOPED TIRE-STUD DESIGNS SHOW PROMISE THAT THE SAFETY AND CONVENIENCE FACTORS OF STUDDED TIRES CAN BE RETAINED-BUT WITH A CONSIDERABLE REDUCTION IN THE AMOUNT OF ROAD WEAR CAUSED BY THEIR USE. IN ADDITION TO A REDUCTION IN WEIGHT AND MINOR DIMENSIONAL CHANGES, MOST OF THESE NEW TIRE STUDS ARE DESIGNED IN SUCH A WAY THAT THE CARBIDE PIN WILL MOVE FARTHER INTO THE STUD BODY IF, AT ANY TIME, THE PROTRUSION OF THE STUD FROM THE TIRE EXCEEDS A CRITICAL LIMIT. (THE GREATER THE PROTRUSION IS, THE GREATER THE IMPACT FORCE IS; AND IT IS HIGH-IMPACT FORCE THAT CAUSES THE ROAD WEAR). WITH THEIR BUILT-IN PROTRUSION-ADJUSTMENT CAPABILITY, THE NEW TIRE STUDS MAINTAIN NEARLY UNIFORM PROTRUSION THROUGHOUT THEIR LIFETIME. THEIR ABILITY TO DO SO IS UNAFFECTED BY DIFFERENCES IN WEAR RESISTANCE OF VARIOUS RUBBER COMPOUNDS, DRIVING SPEEDS, OR ROAD SURFACES TRAVELED. TIRES FITTED WITH THESE NEW STUDS SHOW AN INCREASE OF 75 PERCENT IN COEFFICIENT OF FRICTION ON SMOOTH ICE AS COMPARED TO IDENTICAL TIRES WITHOUT STUDS. COEFFICIENT OF FRICTION DECREASES ONLY ABOUT 5 PERCENT WITH SUCH STUDDED TIRES ON BARE CONCRETE (CEMENT) ROADS. NO DIFFERENCE AT ALL IN PERFORMANCE BETWEEN STUDDED AND UNSTUDDED TIRES HAS BEEN FOUND ON BARE BITUMINOUS PAVEMENT, DRY OR WET.