![]() ![]() Ko compares them to the Michelin Pilot Sport A/S 3 tires that were on the wagon previously. The tires were inflated to 35 psi front and 32 psi rear, as per the Saab manual. Ko reports putting close to 1,000 miles on the DriveGuards during the extra-hot July and August weather. I have old cars with smaller tires, so the test DriveGuards went to my friend Ko Denhamer near Philadelphia, to try out on his 122,000-mile 2003 Saab 9-5 Linear wagon with manual transmission. Curiosity about Bridgestone’s DriveGuard run-flats led to this test. “They’re an excellent touring tire that just happens to be run-flat,” McKenney said. The DriveGuards, with a 65,000-mile wear warranty, come in 19 sizes. Cars that come with run-flat tires also have Tire Pressure Monitoring Systems (TPMS) because otherwise you might not even know the tire was impaired. Not many new cars come with run-flats, but Bridgestone has an arrangement with BMW, most of whose models are so-equipped. The tire will lose its chemical integrity and soften.” Certain types of damage to run-flats-as in sidewall punctures-may not be repairable. Driving any further than that is not recommended, because as the tire rolls it compresses and that compression generates heat-the enemy of rubber. “It will get you home or to the tire shop. “You can drive 50 miles at up to 50 mph,” he said. McKenney said that when a tire is punctured and goes to zero pounds per square inch inflation, rubber inserts in the tire keep its shape and stay on the wheel. Run-flats are generally 20 to 40 percent heavier, but McKenney said that running them eliminates the need to carry a spare-providing a 50-pound weight saving, plus the jack. Ian McKenney, a spokesman for Bridgestone, said in an interview that the DriveGuard line was launched in 2014 as the company’s first run-flat line, and has now been updated as DriveGuard Plus touring tires. Ko Denhamer’s 2003 Saab 9-5 Linear wagon with DriveGuards installed. In a typical self-supporting run-flat today, the reinforced sidewall stays rigid without air pressure-and (as with compact spares) you have 50 miles of safe driving ahead before they should be removed and repaired. ![]() In 1972, Dunlop introduced the Total Mobility Tire and it became standard on certain Rover models. Passenger cars got run-flats in 1958, when Chrysler and Goodyear teamed up on Captive Air tires. The idea goes back to 1934, when Michelin introduced a tire for commuter trains and trolleys that had a “safety rim” inside that could run on a foam lining after a puncture. As the name implies, run-flats resist deflation and can keep you on the road after a puncture. ![]() Or that’s what is supposed to happen-I’ve never successfully used that combination.Īnd another reason why jacks will soon be seen only in thrift shops is the run-flat tire. Many cars today have no spare or jack, and come with small air compressors that work in concert with spray sealant to temporarily repair a flat. These steps are being taken to save weight-which is particularly important in heavy electric cars. Not only are today’s cars being shipped with temporary spares (good for 50 miles or so) but the jack has been largely jettisoned. I mention all of this because spare tires and jacks may soon become part of history. Part of driver’s ed was learning how to change a tire-don’t forget to use the approved jacking points! Bridgestone DriveGuard Plus tires are standard equipment on certain BMW models. Along with the tires as standard equipment was a jack (often in several pieces) and a jack handle. During most of the automobile’s recorded history, cars carried spare tires-sometimes in the early days, several of them (because of frequent punctures) in twin sidemounts or out back. ![]()
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