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!
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.
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.
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.
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?
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!
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.
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.
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.
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.
“…I think I do remember buying “R” rated tires in college…”
Uh…you 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
Nope, I mean R as in speed rating of 106 MPH. I don’ know if R’s are even available now, this was a loooong time ago.
I’m hoping to find some data that says speed rating “X” does / does not hold safety and tread wear in extreme desert heat. Everything I have found so far is just speculation. That’s interesting that most tires are tested in West Texas, do you know in what city? It might help me narrow down my search. Thanks!
San Angelo, TX. to be exact.
Here’s a link to the people that do the testing I think:
http://www.stllabs.com/tti.htm
If nothing else, maybe you could contact them for the info you seek.
San Angelo is but one of many places in west TX where there is a site where tire testing takes place. In fact, many of the tire manufacturers have proving grounds in west TX and many car manufacturers use independent testing outfits to do tire testing - obviously each place is in a different locale.
BTW, many car manufacturers also test in Arizona - Mesa and Yuma come to mind.
So to answer your question, I think you’ll find that all the testing being done is performed for a client - or done for internal consumption - and there will not be any test data available for the general public - except that which is done for and by the government for that particular purpose. I sincerely doubt that there will be any testing specifically geared to your question - except as you indicate - by extension.
BTW tires are also used in the Middle East, which is even hotter than Phoenix. Most of those countries have regulations requiring higher speed ratings - or in absence of regulations, the tire importers only import higher speed rated tires.
And as a further thought, getting a passenger car tire to pass an S rating is easy. Even when speed ratings were introduced 40 years ago - and tires were pretty bad back then - it was uncommon for a tire not to make an S rating. The exceptions are winter tires (for obvious reasons) and the larger tires needed for pickups - LT metrics, for example.
You’re probably right about the availability of any research, I was just hoping… The information about the Middle East and of “S” rated tires is very interesting, tho. It makes me wonder even more about the suitability of “T”'s in the desert. The reason I don’t just run out and buy a set of H or V rated is that they are very hard to find in the quality tires, and are more expensive, sometimes by a lot. And besides, now I am on a quest; this lack of information has brought out my tenacious side. I’ll have to keep looking.
BTW, the testing facilities in Mesa, AZ closed a little while ago and are now home to shopping mall. When you are in one of the biggest cites in America, that amount of land is worth literally a fortune.