Posted by David on October 06, 1997 at 06:50:29:
In Reply to: Why do I need H type instead of T tite type ? posted by Marc Van Nieuwenhove on October 02, 1997 at 15:05:25:
There are many reasons to replace tires with those of equal ratings of the original equiptment type your vehicle came with. Depending where you live some of them are legal ones and the installer/seller can be held responsible for doing or not doing so. A performance (speed) rating which you refer to - "I don't see any reason to use this H type instead of the normal T one" encompasses much, much more than just the top speed at which a tire is certified capable of reaching. Your reference of "normal T" is quite interesting? Why is a T rated tire a normal one? The speed rating catagories actualy begin at A1 = 3mph and progress, through an alpha numeric system, to Z = 186 + mph. The most commonly used passenger car classes are Q = 100mph, R = 106mph, S = 112, T = 118mph, U = 124mph, H = 130mph V = 149 mph, W = 168mph, Y = 186mph & Z = 186+mph.
The origin of these performance rating was indeed to make sure a tire fitted to a vehicle had the ability to match the top speed capability of that vehicle, and in some countries that is the legality I mentioned earlier. But to lend a very generic technical twist to this, the components and construction of a tire basicly improve or are better in order to enable a tire to reach a higher rating. Those things then will generaly inturn, increase a tires traction and control abilities as well, in other words, improve the handling, braking, steering, cornering ability, etc., etc., etc.. For "real world" realtion, most people don't drive their vehicle on a regular or continual basis at 112, 118, 124, 130 .............186+mph. What the average "real world" expirience offers is how well a tire reacts and responds to what is asked of of to do, the above mentioned catagories.
Now, as indicated in your brief description, you have been driving on H rated tires, you are acustomed to a certain level of all the aboved mentioned characteristics of your tires, by replacing them with a lower level, performance rated tire you will be downgrading the tires ability to respond to your imputs in the same way you have been accustomed of them doing. I don't know where you drive but choose or imagine a incident where you have to make a sudden manuver, (accident avoidance, sudden lane change, braking rapidly etc.) do you want your vehicle to do what you are asing it to do at least as well or better as it was able before?
For the $$ differnce (usually not signifigant in comparison to the alternative.......) I would recomend you make you decision factoring these things, not just how fast a tire can go.