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After repeated condemnation of my wanton disregard for the status quo by tire salesmen and the "experts" here on this forum I have decided to do the unthinkable and drive on presumeably longer lasting H speed rated tires instead of Z (or Y or W). I was warned by salesmen that "my car will sloth around like a heavy boat because the sidewalls are sloppy on H rated tires". Or "it is dangerous to put a lower speed rating on a car then the OEM".

Findings: Absolutely no frigging difference in handling, control, or traction. My scientific findings are based on a highly technical analysis - driving around freeway onramps and turning the steering wheel "really fast" to feel the resultant car response. The sidewalls ARE NOT flimsy. Remember, this is still a low profile, .45 aspect ratio tire.

The new tires I have are H rated, 500 treadwear Yokahama H4s. The tires that came off were Z rated, 400 treadwear Conti Extreme contacts. Prior to that the tires were Y or W rated, 360 treadwear SP5000s

Until someone comes up with real measureable performance criteria and data for tire characteristics (which we'll never see from the tire industry because vagueness and obscurity are key to their marketing strategy) I hereby say (*$%$%^& to the necessity of super high speed and price tires.

Now here's where I can be wrong (and it's happened once or twice before in my life):

1. The Yokos might wear down just as fast as the previous tires (about 25k miles) so going to H rated my be completely useless.

2. The performance difference might actually exist but it's marginal and some people are willing to pay a heavy price for marginable performance. I cannot measure it though. And neither can anyone else unless you do some controlled experiment. And I've read all kinds of so called "controlled experiments" which don't mean squat. Anyone's qualitative description of how a tire handles is pathetically useless.

3. H ratings are good for 130 mph whereas Z, Y, and W tires are way over that. Since I'm governor limited to 130 I don't see this as an issue. But this IS the real difference between these type of tires.

Esquire6

per tire. Do you also use 87 octane gas?

2002ar

The speed rating doesn't necessarily equate to how well a tire performs. Some H-rated tires perform as well as, or nearly as well as, their faster-wearing higher-speed-rated breathern.

2002ar

LOL! H-rated tires are good for 130 MPH; how fast do you drive?

paulroad

JK.. in the real world depending on how you drive you personally will not feel the difference. Possibly because you would know the feel.

I have to assume you are a more sedate driver, you are not taking on ramps and highway curves at the limit.. just for the fun/feel of it.
You stay within the normal speed limits, transport the kids to soccer, etc. (no offense ment)

The low aspect has no bearing on the speed rating nor does the low aspect indicate a soft or hard sidewall. if you compare the same tire in differnt speed ratings a higher speed rate will have a firmer side wall.

The speed rating is an idication of how the tire is constructed. Not just the rubber compond but the interal belts, the weave of the belts, the materials used in their construction, etc.

The higher the speed rating.. the stonger the materials and mthoods used. I don't mean physically stronger or harder, I mean resistance to heat and to "flying appart".

In a nutshell.. do you play any sport? Would you wear a pair of Keds to play Baseball or Basketball? They do the same thing as Nike or Adidas do... but there is a difference right?

You just put Keds on your atheletic car. If this works for you then its great, but understnd the difference.

paulroad

I'm on my second set as the first set gave me wll over 30K of use including a track day. At $98.00 how can you go wrong?

a62.7t4ceo

Choose a tire based on your driving. Speed ratings were created to match the top speed capability of the vehicles they're applied to. You won't notice a difference between an H and a Z in "normal" driving conditions, however, you would notice a difference as higher speeds. As long as you don't compromise on the load rating, you're fine. The lowest I'd go is an H.

john in cincy

to the stiffness of the tire. It was always my understanding that the cause of tire failure due to speed was related to the fact that a tire deforms slightly from round where it meets the road and that a failure occurs when the deformation does not bounce back prior to the next revolution. As such, a higher speed rated tire is stiffer to prevent this failure. Along these lines, it has also been my understanding that an underinflated tire at high speeds could fail well below the speed rating. In other words, if you were going to be driving anywhere near the speed rating, you better make sure your tires are properly inflated.

paulroad

Take any car, put on H rated tires, take a on ramp and find out what speed you hear the tires whine. 40 mph perhaps? If you could switch to same load rated tires with a higher speed rating and you will not hear the whine at that speed, in fact you will find you can take the turn faster.

Speed ratings have much more to do with contruction of the tire. The speed rating is an end result of that construction.

paulroad

And you will find on track days, that we overinflate the tires to further increase the stiffness.

But again it comes down to how do you drive? And what you need.