I'm looking to replace my Michelens. The Bridgestone Potenza RE950 gets good ratings on tirerack, but it doesn't come in "V" speed rating only "H". What exactly does speed rating mean anyhow? I don't think I'll ever go 140 or 130. So what does it really do to have a "V" verses an "H" rated tire anyhow?

 

Don’t quote me, but I think “H” is rated for 130MPH and “V” is 149.
“Z” is something like 180 or so.

One of the online tire sites probably has a chart.

Shawn S

 

Generally speaking the higher the rating the softer the tire. Thus, the tire wears out quicker. However, the softer the tire the better the grip. Manufacturers have been trying for years to find that perfect balance between grip and wear, but for the here and now we are stuck with speed ratings. Just remember that the rating is for "sustained" speed. The CLS does not need a tire rated for a sustained 180 mph. However, as mentioned if you are the type that desires maximum grip and are willing to get new tires every 12k miles go for the highest speed rating.

 

i think it's the opposite...the higher the rating the harder the tire. This is because of the extra heat it will need to handle at the higher speeds. At sustained higher speeds, the tires will be hotter than at normal speeds. If they are already soft, they will get gooier and that is not good for handling because of flexing in the sidewall.


But i think there is a noticable effect from going to a higher rating even if you don't drive at higher speeds because the tire will be stiffer/harder, making handling feel better because of less flex in the tire during cornering.

 

They are softer because cars that go that fast need the traction to accelerate at full potential. If the Z rated tires were harder sports cars would have H tires on them for grip---which is not the case. It is mainly the belting in the treads that dictate the rated speed, compound has less to do with it.

 

NOPE, you're way off. You've obviously never had a high speed rated tire on your car. If you did you'd know they wear out fast. The heat you mention is disipated more by the softer rubber. It is the harder compounds that retain more heat. Truck tires are very hard and you 'll never see a Z rated truck tire. Well . . ... except for those trucks that have non factory rims. FYI the tread compound and the side wall compound are completely different. The tires tread does not have to adhere to steel cords as does the side wall.

 

Lets make it simple for Jwong... H rated tires are noisy on the Highway...well atleast all the H rated I owned.. all depends on what your driving conditions are and if you want an ALL SEASON tire.. I recommend you talk to Chikai if your gonna upgrade your tire on your factory rim.. he got some nice meats and they are holding up good..

Smitty

 

i've never had a high speed rated tire on my car, obviously?

i have z-rated kuhmos on my car right now, and they are way stiffer than the stock tires.

You could've just said that it is the construction instead of the compounds that make them stiffer,

but thanks anyway for pointing out that i am way off and "OBVIOUSLY" never had a high speed rated tire on my car just because i'm not a tire expert.

 

Thanks smitty. I live in sunny San Jose where it only rains a fews months out of the year. I don't drive fast at least not anywhere near 130mph and I'm only interested in getting tires which are quite on the freeway, but I don't want to get something where I'll spin out going around a freeway exit. Thanks for help

 

Speed Rating
The speed rating denotes the speed at which a tire is designed to be driven for extended periods of time. The ratings range from 99 miles per hour (mph) to 186 mph. These ratings are listed below. Note: You may not find this information on all tires because it is not required by law.


Letter Rating Speed Rating
Q 99 mph
R 106 mph
S 112 mph
T 118 mph
U 124 mph
H 130 mph
V 149 mph
W 168* mph
Y 186* mph

* For tires with a maximum speed capability over 149 mph, tire manufacturers sometimes use the letters ZR. For those with a maximum speed capability over 186 mph, tire manufacturers always use the letters ZR.

 

Another good source for tire info:

http://www.nhtsa.dot.gov/cars/testing/utqg/

 

I had Toyo Proxes FZ-4 45 series on my previous car. Tey were W-rated, which is 168mph! Agreed, they didnt last long.

 

Another thing to consider is that higher speed rated tires are made to a higher level of safety and quality. They have to be to survive at the higher speeds. This means you'll have a greater margin of safety at legal speeds.

I made a mistake on my previous SHO of trying to save a few bucks and getting some Yokohama H rated tires. The originals were Z rated Goodyear Eagles. Eventually two of the four tires failed from tread separation. They were all replaced on warranty at my insistance. However, I compromised my, and my family's safety by riding on these sub-standard tires.

In designing the suspension, engineers have to assume a level of performance from the tires. Ours CLs were designed for Z rated ones and I'll ride on no less.

If you're willing to drive like "granny" then I guess it doesn't matter.

 

My 01 CLS did not come with Z rated tires. Are the new/last CLS' coming with Z rated tires? If they are still not coming with Z rated tires how is it that they are designed for them?

 

They come with V rated tires (one step down from Z, because W speed rated tires are also Z rated :sqnteek: ). The load rating is 93, and at least I couldn't find 93 load rated tires that also didn't have a V or Z speed rating.

Things to take into consideration when buying new tires:

• Size (sidewall height, odometer accuracy...).
• Load rating.
• Speed rating.
• Tread compounds and construction (which translate to type of tire and UTOG rating).
• Tire overall construction (and weight).

And as Klamalama said, a lot of these issues which seem separate are actually related in the marketing of tires. For instance, you won't find a tire with a high speed rating and otherwise crappy construciton or UTOG temperature rating. Quality tires usually have their quality in all of the above factors, and visa versa.

The stock CL-S tire is XL load rated with 93 at 'normal' operating pressures. It is V speed rated. It is an all-season touring tire that few would consider performance oriented.

 

I have these in 235/45/17 stock rim on my 2001 cls...

about 10k miles now... no problems whatsoever
tread wear is good....have hit 110mph

as far as handling...it is better than stock, alot better in rain
don't know if they are as good as the BS s-3 though...

 

For what it is worth, it is my understanding tht the Letter Rating Speed Rating
Q 99 mph
R 106 mph
S 112 mph
T 118 mph
U 124 mph
H 130 mph
V 149 mph
W 168 mph
Y 186 mph
only pertains to at what sustained speeds the tire will not fall apart at due to heat build up etc.. For the tread compound you should be looking at the tread wear rating. These numbers can be found on the sidewall next to the sizing information. A tread wear rating of 360 means that the tire is of a harder compound and will thus last longer. You will find this number to be about 360 on most all season tires. Most high performance ZR rated tires have tread wear rating between 100 and 250 thus corelating to a softer tread compound usualy equating to better traction while sacrificing tire life. I know that you can get ZR rated tires with a high treadwear rating. I had some Dunlops, SP something thousand, that were ZR and had a 320 treadwear rating. They were great tires and had half tread or more atfter 20,000 miles. I routinely did 115mph plus un these tires and maintained them a 38psi. Never failed and always smooth. when tires come in to question I would always go for a ZR tire. noticable improvements in handling for only a $100 or so more.

hope this helps,

Jim

 

My Kumho ECSTA 711 H rated tire is supposed to have a longer treadlife than my old Kumho ECSTA 712 Z rated tire (per tireracks info)
But that's the only thing that was rated better than my old Z rated Kumho.

 

As the speed rating goes up, the sidewall and tread get's stiffer. Also, the compound get's softer to give the tire more grip.

Higher rated tires (Z versus an H) will be stiffer on the sidewall, but the tread wears quicker (due to it's soft compound).

If you put H rated tires on and then drive at 150 MPH, you risk the tire bursting (as the tire spins up, the center pulls out -- centrifugal force; if you watch dragsters heat up the tires at the tree you'll know what I mean). The higher rated tires are stiffer to stop the tire from pulling as much).

You can run lower rated tires, just keep that in the back of your mind if you ever consider cranking her up past the rating of your tire, otherwise there's a chance of someone having to peel you off the pavement.

Also, the suspension of the car is designed for rebounds tuned to a V rated tire. Going stiffer (Z) or softer (H), can impact how the car handles over bumps (i.e. more bounce or jitter). Not a big deal if you don't performance drive it, but up to you.

 

You should come ot the meets.