Speed ratings, tire construction?

[Guest turboman]

I've never been able to find out the exact construction differences between the same size and model tire with several speed ratings.

 

Once I heard the carcasses were exactly the same but the x-ray inspections are much stricter on the higher speed ratings.

 

Are they all made the same and the final inspector decides what the speed rating should be?

[blackheart]

Check Tirerack's site. They have all kinds of great tech help free.

 

http://www.tirerack.com/tires/tiretech/general/speed.jsp

[Guest turboman]

Check Tirerack's site. They have all kinds of great tech help free.

 

http://www.tirerack.com/tires/tiretech/general/speed.jsp

 

Couldn't find what I want there (TireRack). All they have (last time I looked) was the various maximum speeds of the different ratings.

 

I want to know if a higher speed rating tire carcass has more sidewall plies, different belt angles, durometer readings, etc.

 

Thanks.

[sduford]

I think that would depend on each tire brand/model. So you would be more likely to find that info on the manufacturer's site.

[dustinw]

I've noticed that it's very tough to get comprehensive information about tire construction. Each manufacturer calls things by different names. They understandably have trade secrets and things that they want/need to keep to themselves for competitive reasons. However, why isn't anyone disecting the tires and figuring the stuff out and letting the consuming public in on some of the info?

[Guest turboman]

It's not a life or death kinda thing for me it's just that what I originally heard was that before the inspection the tires are all alike. In the inspection they run them up to a speed on the roller and the ones that survive the highest speed get the highest rating.

 

But that wouldn't make any sense. If a one construction method tire failed at one speed then they would try another same construction tire at a lower speed. And keep going down until it passes. Future tires built to that specification then have the lower rating.

 

It has to be they build stronger tires (more belts, different angles, different heat treatment and curing time) with the intent of them being run faster and then they test that construction to be sure it will stand up for so long on the pressure roller. But it can't be too heavy or it would overheat.

 

But in many cases I've seen a higher speed rating in the same tire costs the same as a slower rating in the same tire...

 

..my head just exploded. Some things man just is not meant to know.

Nevermind.... Not worth the effort. It doesn't really matter either way.

[Xenonk]

it's little variances in the compound and how the steel plies are put together, but it's enough how well the tire can hold up to the speeds of what they can withold. It's hard for me to find a really needed use for Z rated (168+mph) unless you plan to track the car. But from what I know, it's just how the steel plies dont expand as much and holds a better composure at higher speeds. Heat will beat up on it regardless on the compound causing the tire to eventually wear down. Remember, a corded ZR rated tire isnt any better than a corded HR rated tire.

 

As far as prices go, it's adjusted to what the common tire size vs. the kind of cars that would use them to their expected speed use.

 

Keefe

[XT6Wagon]

One thing I will say on this... if you plan on remotely "high speed" use in high temps, get a speed rated tire. Running 100mph for a couple hours straight in 115 degree temps is going to damage or distroy tires that are not Z rated. ask me how I know. With something like a lower end S or T rated tire it will be flat dangerous even though you are running below thier speed rating.