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Originally Posted by beatr911
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Does this mean that the tires on your California vehicles should be changed part way through their treadlife due to the possibility of heat related failure?
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Perhaps. This is an age vs heat history kind of thing. Clearly, tires that have been operated at high speeds have generated more heat than tires that have been used where the speeds are confined to 35 mph.
5 states have been identified as having the most heat related tire failures - something on the order of 90% - more or less in this order: AZ, CA, NV, TX, and FL. I should point out that this statistic is "number of tires" and is partially driven by population.
FL seems the odd man out here, but if you look at the temperature history of FL, you'll notice that it never gets cold in FL - it stays warm year round. This is probably due to FL being basically a peninsula, and almost completely surrounded by water. The maximum temperature is reduced, but the low temperatures are also increased.
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Originally Posted by beatr911
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When I lived in Barstow and driving in 117 degree heat in the desert the tire temperatures were way less than when I autocrossed on a pleasant summer day in Washington state. In either case I experienced no heat related failures.
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Needless to say, autocrossing generates a lot of heat, but it also wears tires out quickly - ergo, the tires are worn out before their heat history catches up with them.
Not to mention that autocrossing is typically a short duration event and the heat that is generated is basically on the surface and doesn't have much of a chance to affect the inner structure of the tire where heat damage could cause potential problems.
Plus, autocross tires are typically high speed rated. (H and higher) and aren't as affected by temperature as S and T rated tires are.
Heat related tire failures are fairly rare. Even the infamous Firestone Wilderness AT only had failure rates in fractions of a percent. A person in AZ, for example, could go through life thoroughly abusing tires and statistically it's possible that he would never see one. The problem is that a tire failure is potentially a life threatening event! Which is why you will hear lots of warnings that seem overly dramatic.
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Originally Posted by beatr911
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I'm not saying used tires is a good or bad idea, even in California.
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Well, I'm saying it: If you live in AZ, CA, NV, TX, and FL, DO NOT buy used tires.
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Originally Posted by beatr911
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Like buying anything used, you may or may not have problems and there typically is no warranty. Most people shy away from used tires because they don't know what to look for when inspecting and get a little irrational on the safety issue (gee, what if I have a flat?). Unless the tire is ozone cracked, has cuts, bulges, etc that would cause it to be changed out anyway on the vehicle on which it occurred, it's probably OK.
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The problem here is that most people not only do not know WHAT to look for, they don't even know to look. Plus many purveyors of used tires do not inspect the tires they sell. Potentially dangerous tires ARE NOT screened out. It's these unscrupulous dealers that ruin it for everyone.
In order to put some numbers to this, a private investigator went out and purchased over 100 used tires. No criteria, he just purchased what was for sale at the corner used tire lot. Then the tires were inspected by experts. 25% of these were judged to be unfit for sale. There were unrepaired punctures (with the nails still in them!), tires worn below the legal limit, - and the worst part was there were obviously separated tires in the mix. This is a very disturbing statistic!
Don't get me wrong - I'm a bit of a cheapskate - but I know what to look for in a tire, and I will never, ever buy a used tire. The risk is just too high for my taste.