Q vs H rated Winter Tires - Forester

Do you go that fast in the Summer?? If so, it probally doesn't matter which tire you get because you will not be long for this world...

All kidding aside, I have placed lower speed rated (T) tires on a car that came stock with (H) rated and I noticed that the car didn't handle as well through the corners. I don't know if this is because of a 'less-stiff' sidewall, or just the particular tires I was comparing, but I would imagine that if you went down a speed rating in a winter tire, the 'perhaps' lack of handling would be offset by the superior traction. Of course, where you live, how much snow, how long you will have them on the car all would help the decision making process. Maybe not much help, but my $.02. Good Luck

So what I'm hearing is that I should definitely get an H rated winter tire if that's what the Forester came with. Funny how only one of the four tire dealers I went to even asked what the tire rating was. Just to add some info, I live in Guelph, Ontario, Canada. We can get some pretty harsh winters here, especially when driving on the country roads in this area.

First of all, the speed rating only applies to dry regular pavement. Anyone driving 99 MPH in deep snow is an idiot.

There are very few V-rated winter tires (Nokian WR is one).

Most tire installers will make an exception for winter tires with a lower speed rating. I recall being at a tire store where someone asked about installer slower speed rated tires than factory to save money. The installer said he'd install them only if the buyer signed a waiver saying that he understood that this fact. I'd hope that for winter tires, the installer would present all the safety info, and make the buyer sign a statement that he understands there are limits to winter tires.

Can you cite even one state law that supports your claim?

-- Vic Roberts Replace xxx with vdr in e-mail address.

Hi,

I've heard this is the case in many European countries, but as for state laws here in the US, that's a new one on me. Here in SoCal several tire dealers have told me the same thing: stay at or above the factory weight ratings and use the speed ratings to decide how much "performance" you think you need (remembering tire life is somewhat inversely proportional to speed rating.) For example, my Subie came w/ "S" rated tires, my Camry SE w/ "V" rated. While it's nice to think I'd be okay at 139 mph or whatever the "V" rating is good for, the reality is that any of the ratings is gonna be safe at "normal" freeway speeds of 65-75 mph, and being stuck in traffic at 10 mph certainly doesn't require much "performance" so AFAIC I COULD put "S" rated tires on the Camry and be as safe as the Subie using MY driving conditions as the determinent. Naturally, YMMV.

Rick

according to the nhtsa

"the speed rating denotes the speed at which a tire is designed to be driven for extended periods of time." the lowest rating shown is "Q", which is listed as 99 mph, whereas "H" is 130 mph. note that there is absolutely no indication there, or anywhere else, that speed rating correlates to any other tire characteristic, such as handling or traction. its only bearing on safety is if you exceed the rated speed, so i'd be curious to hear how often you manage to drive your '04 forester faster than 99 mph "for extended periods of time".

in fact, i would actually expect snow tires to have a lower speed rating than a comparable quality summer tire, since the speed rating is mostly based on the ability to dissipate and withstand heat, which isn't a big issue in winter conditions. (but even a lowly "Q" rating doesn't mean that the snow tire will self-destruct on the first warm day of spring.)

since the *lowest* speed rating starts at 99 mph, i think speed ratings, especially ones that go all the way up to 186+ mph, are just another testosterone-rich marketing gimmick, aimed at the street racing wannabe crowd. (yes, i know that some cars can go that fast, but the tire companies sell a lot more "fast tires" than there are "fast cars".)

it sounds to me like the tire merchant was engaging in a little creative upselling. caveat emptor.

....... tom klein

tom klein wrote: > note that there is absolutely no indication there, or anywhere else, > that speed rating correlates to any other tire characteristic, such as > handling or traction. its only bearing on safety is if you exceed the > rated speed, so i'd be curious to hear how often you manage to drive > your '04 forester faster than 99 mph "for extended periods of time".

Perhaps there's no required correlation. However - most tires designed for extremely good handling will be in the upper ranges of the speed ratings. There are some V-rated tires that are known to handle better than other Z/W/Y rated tires of the same size.

The speed ratings actually aren't required by Federal law. Even the load index isn't required. It's pretty much just industry norms that speed-ratings and load indices are used.

It's extremely common for winter tires to be of different size and/or speed-rating that the original tires.

A Google search did turn up the fact that Maine has a law that requires that load AND speed ratings for replacement tires be at least as high as the original tires. I can understand the load rating but not the speed rating.

I did not find any other state laws that specify speed ratings, but there may be some out there. Certainly not all states have the same laws.

-- Vic Roberts Replace xxx with vdr in e-mail address.

You claim your statement about a law is correct because it is logical AND you decided not to bother find specific instances! I would love to see you in court :-)

-- Vic Roberts Replace xxx with vdr in e-mail address.

That's been my experience as well. Over 20 yrs ago I had H rated original tires on my chrysler TC3 car and needed to change early because those Firestone originals were showing serious weakness at only 32Kkms (20K miles). Those H rated tires had very good winter traction, both the tread and side wall were a soft rubber with good adhesion. My car couldn't come close to the very high speed rating of the H tires, it's maximum speed being only 60% of the rating. My choice of replacement tire was a Michelin all season. I wanted to go from the original 60 profile to 70, for slightly less harsh a ride. According to my calculations the width of tire I selected would correct my high speedometer reading. The weight bearing capacity of the 70 profile Michelins was slightly higher than the originals and both had about 50% more weight capability than that light car would ever be.

Sears wouldn't mount the Michelins saying they would not mount a different tire than originals even though it was more than capable than handling my car.

So a Chrysler dealer who had a bit more common sense got the sale. They agreed that the different size Michelins were more than up to the task. Those Michelins performed very well, traction equal to the original Firestones and of course a much lower rate of wear plus more durable. Cornering was slightly less crisp but still very good. Oh yes I didn't sign any waiver of responsibility.

For a H rated summer tires it is usual to use T rated winter tires (190 km/h) = one step down. According to my experience it is not advisable to use high rated (summer) tires. High rated tires are constructed to resist high speeds that are not typically used, so they don't warm up to optimal temperature (for optimal grip) - they stay cold (unless you drive aggressively). Jiri

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... or practising for a Rally ...

I mean come on, this is Subaru after all.