Yesterday I had a tire blowout. When I visited a tire shop (Costco Tire Center) afterward, the person there told me that my tires are under-rated for my vehicle. My vehicle is a Honda Accord 2002, which Costco's computer says requires a V rating. The tire that blew out has an H rating.

When I had the previous tires installed (at Sam's Club), they did not mention speed ratings. I just trusted them to do the right thing. Now Costco's rep says that my blowout is typical for an under-rated tire. Specifically, he told me that a lower speed rating means weaker sidewalls, so the chance for a blowout like this increases. He continued that my Accord's suspension is tuned for a certain speed rating, so even if I don't reach V speeds, it's still important for my tires to be V-rated.

I drive on a curvy highway twice a day, so I do a lot of turning/curving at 60-70 mph, so I can see how this might be a challenge for tire sidewalls. (The tire blew out on that highway.)

Do you agree with the claim that a lower speed rating can lead to blowouts?

tire blowout.

  • What is the load rating of the blown tire?
    – NitroxDM
    Jan 15 '13 at 16:34
  • Sounds like they just wanted to sell you the more-expensive tires. If you bought them under this misleading information, I'd go back and speak to a manager and argue until they refund the price difference. (They certainly don't want to exchange them; the labor would be much more than the price difference.) Apr 24 '13 at 14:42

The Info provided by COSTCO is on paper correct, if you were say using a tire with a speed rating of 118 mph (T), and you were in Germany cruising at 140 mph, the tire could overheat and cause this problem.

However, in your case, you just had a flat tire driven on flat. If they check the tread, area, or the valve stem, from the take-off tire, they will find the puncture that caused the initial lost of air.

  • 2
    Agreed. Speed rating is not a problem in this specific case. Your H rated takeoff tire is good to 130MPH. The thing about the suspension tuning is BS in my opinion. The blowout was almost certainly caused by an underinflated tire, which caused overheating of the tire due to all the flexing.
    – mac
    Jan 11 '13 at 16:39
  • NA and Turbo MR2s have the exact same chassis. NA came with H rated tires and Turbo came with V rated tires (both of which happen to match the top speed of the particular configuration). Speed rating is just that, a speed rating. However, higher speed ratings often have higher allowable load too. If you have a tire that the load rating is too low you could have a blowout. Apr 25 '13 at 17:57

The fact is that (H) and (V) rated tires are very similar in their speed ratings. In fact, they are right next to each other on the speed scale: 130 MPH for (H) and 149 MPH for (V). Because of the speeds at which you travel on that highway, the difference between the top end of these ratings is insignificant.
Your car is not a 5,000 pound Porsche Cayenne either. Good (H) rated tires can handle moderate twists in an Accord just fine.
However, it is true that you should always match your tires to the speed rating for the car. If you were driving on a (Q) speed-rated tire - which is only good for 99 MPH - I would be more likely to lay blame on its speed rating.

  • 2
    Your Q rated tire example would still only be a problem when travelling over 99mph. Load ratings, on the other hand, must be taken into account at any speed.
    – mac
    Apr 24 '13 at 20:15
  • @mac Excellent point. May 20 '13 at 2:57

Speed rating should not be the problem, according to your top speed. However, other factors may cause a tire to blowout. Considering the tire speed numbers on this website Tire speed rating, you should be fine. But a puncture, under or over inflated tire, and low load index could be considered.

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