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Best tire rating for the desert heat?

I live in Phoenix, where summer temps are often 110 degrees or more, and the asphalt can reach 130+ degrees. I'm looking to replace the tires on my Toyota Sienna and Camry, and I'm concerned that the standard "T" speed rating isn't really high enough for this area. When you see the number of cars on the side of the road in the summer with blown tires, you start to wonder... I know that under-inflation is the leading cause of tire failure nationwide, but what about in the desert? I've written to three manufacturers and they all insist that their T rated tires are fine for desert use, and that even their high-mileage tires (75K+ miles) are guaranteed to last here. I'm skeptical, but I can't find any test or review data specifically for the desert. Does anyone have any advice or information about buying a U, H, or V rated tire over a T rated one, other than "it couldn't hurt?" Thanks!


  • edited March 2008
    They should be OK, but it is your car, if you feel safer going to a higher rating, then do so, you likely will be a little safer. However remember that a lot of people don't believe what the auto manufacturer says and they buy cheaper lower rated tyres. I suspect many of those you have seen have done just that.
  • edited March 2008
    A higher rated tire mainly reflects a tires ability to retain strength at higher temps(from speed). ZThere is a factor of safety however using a t-rated and keeping air pressure proper always is safer than v-rated with low/neglected air pressure.
  • edited March 2008
    Yup, speed rating goes hand in hand with temperature rating.

    And while T rated tires are OK, H, V and W, etc (you won't find any U, BTW) will be better.

    And testing results? Uh..... the speed rating test IS a form of a temperature test - the faster you go, the more heat is generated in the tire.
  • edited March 2008
    Interesting observation that many people believe the "T" rating is too *high*. That is related to something I wondered about the rating especially for the desert -- for the average family sedan, do car manufacturers put on tires that meet the absolute minimum to cut costs, or do they go a little higher to minimize safety lawsuits? Or do they shoot for the middle and not worry about the temp extremes either hot or cold?
  • edited March 2008
    I think you will find that car manufacturers have a great deal of inertia - they are very slow to react and when they do react, they tend to take baby step.

    Case in point: Firestone / Ford. It was obvious that most of the problems occurred in AZ, CA, NV, TX, and FL. So in response, did the car manufacturers specify higher temperature rated tires (higher speed ratings)? Well, sort of. They realized the general public seems to think that the speed ratings mean the absolute maximum speed the tire can withstand - that the general public thinks that means they only need a tire rated for 85 mph.

    So what many of the car manufacturers did instead was specify LARGER tires - which is also better, but is a small step compared to a speed rating change!

    But some actually did increase the speed rating specified. But the problem here is that the general public tends to want cheap tires and AZ, CA, TX, NV, and FL are no exception - and that means S and T rated tires.

    Personally, I think these states ought to specify at least H rated tires for the safety of the buying public - but if car manufacturers have inertia, government is even worse!
  • edited March 2008
    Whatever you buy, watch the pressures. High pressure can be dangerous as the tire can separate from overpressure. If you put 35 pounds in in the evening and the temperature goes up to 110 the next day your tires could overinflate. If they are damaged by this the warranty will be voided, as I have seen the tire companies deny warranty due to overpressure. I think 130 degrees may be a low guess on the temperatures the tires maybe experience.
  • edited March 2008
    Living in the southwest desert heat myself, I can tell you I've never worried about the speed rating on my tires. I typically go w/ whatever size is recommended, and whatever happens to be on sale at the tire store. I drive A LOT. approx. 200 miles per day and have never had a blow out. I'd say the most important thing is, as others have mentioned, to keep the tires inflated properly; and replace them when they're worn.
  • edited March 2008
    Now that you mention it, I think I do remember buying "R" rated tires in college because that's all I could afford, and besides, my junker could never go more than 85 MPH anyway, so no problem, right? :-)

    Lots of good input here, and I appreciate the advice. Does anyone know of where I might find some actual tire-desert test data? I doubt the tire manufacturers will release their test data. Maybe the Insurance Institute? Thanks.
  • edited March 2008
    The key here is keeping the proper tire pressure rather than the speed rating. When tires are underinflated they flex and squirm more, and that generates heat, and combined with high heat can result in failure. Higher speed ratings can help, simply because they typically have stiffer sidewalls and produce less flexing and squirming under a given set of circumstances, but I think the real key is a good pressure gage.
  • edited March 2008
    ".....I think I do remember buying "R" rated tires in college...." don't mean "R rated" as in "Radial" - do you?

    "......Does anyone know of where I might find some actual tire-desert test data?......."

    What kind of test data do you think they might have?

    If it is any consequence, most tire testing takes place in west TX and it gets pretty warm there
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