All-season tires: car tires, tread wear[SIZE=-1]Until now, you had to trust the Uniform Tire Quality tread-wear grades found on a tire’s sidewall and a tire?s tread-wear warranty to tell you how long your tires would last. We discovered in our new tread-wear tests that some tire makers vastly overstate tread wear while others underestimate. We commissioned a tire-testing contractor to run accelerated wear tests of our all-season tires, closely following the same procedures specified by the government for manufacturers. Four tires from each tire model were tested separately in pairs in two convoys of nearly identical vehicles for 6,400 miles, following an 800-mile break-in with periodic tread-wear measurements. Our tests varied mainly in that each of our convoys consisted of 10 vehicles rather than the 4-vehicle limit required by the government tests. Some scores followed the tire makers? claims fairly closely. Four models that had modest tread-wear grades (520 to 560) and warranties (65,000 to 75,000 miles) scored fair in our wear-test Ratings (See Tread life in the Ratings chart). Likewise, the Bridgestone Turanza LS-T, with a 700 tread-wear rating and an 80,000-mile warranty, had excellent tread wear. The Michelin HydroEdge, with sidewall ratings of 800 and a warranty of 90,000 miles, had a very good score in our tests. Others didn?t come close. The Kelly Navigator Platinum TE claims a high 700 grade and 80,000-mile warranty, but managed only a fair rating. Conversely, the Dayton Grenadier PLE has a more modest 640 grade and an 80,000-mile warranty, but has excellent wear rating based on our tests. Use our tread-wear Ratings (See Tread life in the Ratings chart) as your indicator of wear potential. The warranty is your second-best option, as a failure to meet this claim could mean that the manufacturer must reimburse you some of the tire?s price. Use UTQG tread-wear grades on the sidewall as your third option, but only as a loose guideline. Tread life is important, but it shouldn?t outweigh braking, handling, and other critical safety factors. Indeed, tires that last too long may pose a safety risk, since rubber compounds deteriorate with age. That has led some automakers to recommend discarding tires after six years, regardless of wear. So far, the list includes BMW, DaimlerChrysler, Ford, Mazda, and Volkswagen, though not General Motors. We recommend that you check your tires regularly for wear, cuts, and bulges, and replace tires older than 10 years. The good news from our tests of all-season tires is that tires continue to improve, so finding a tire that meets your needs is less difficult. TIRES THAT FIT THE CLIME All-season tires come in sizes to fit everything from small cars to full-sized SUVs and pickups. We selected a common size, P205/65R15, for both types, and our judgments serve as a yardstick for 14- through 17-inch sizes of the same models. All-season tires are standard on most new cars and light trucks, and they accounted for 83 percent of the replacement market last year. While that?s down 2 percent from the year before, these tires? competent year-round traction, comfortable ride, and long tread life still provide the best compromise for most drivers. We selected our all-season models from premium and upper-midlevel lines with S (112 mph) or T (118 mph) speed ratings. Tread-wear warranties run from 65,000 to 100,000 miles. Premium all-season tires continue to improve, our tests show. *However, all-season tires aren?t the best in the wake of a severe winter storm, especially if you must be on road before the highway crews. Winter tires have treads with more biting edges for better grip on snow and ice, while their softer compound remains flexible even in extremely low temperatures. (See our report on winter tires.) On cleared roads, however, they might not grip as well as all-season tires, and they often wear more quickly. They do not have tread-wear warranties or grades and should be removed in the spring. This report was originally published in November 2005, the information presented here is current.[/SIZE] [SIZE=-1]Subscribe now![/SIZE]
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