Saw several things mentioned here I wanted to comment on.
There seems to be an assumption that a higher (speed) rated tires enjoy shorter stopping distances wet or dry as function of the speed rating. That isn't entirely accurate. Stopping distance is a function of the rubber compound (esp dry) and tread design (esp wet), not a directly function of the construction of the tire. If you see a correlation in test data - it is just that, a correlation. By coincidence or design, higher speed rated tires do tend towards softer compounds. But softer compounds in and of themselves do not yield a higher speed rating. It does yield better adhesion.
If you are interested in stronger (safer) tires: Look at the speed rating (with H being the minimal cutoff where possible).
If you are interested in shorter stopping distances: Look at the compound (the biggest difference between summer compounds vs all-season compounds).
Tread designs offer a direct impact on WET braking. More R&D is almost certainly put into H and above tires. I really haven't noticed much if any change in the S and T tires still on the market today from decades ago.
There seems to be an assumption that lower rated tires last longer. Again, this is more of a function of harder rubber compounds favored for cheaper S and T tires. For longevity don't look at the speed rating, look at the treadwear rating. If for example you have an S or T tire with a 400 treadwear and an H+ tire with a 400 from the same manufacturer... guess what? They will last the same. a 300 treadwear rated tire will last abou 75% the life of a 400 treadwear rated tire. And so on. Cross brand treadwear ratings aren't technically identical but IMHO they are close enough, say within 5% of each if we're talking major brands. (Personally I like tires in the mid to low 300s for general/aggressive driving or even an occasional on-course jaunt but I recognize most folks prefer longevity over adhesion)
I've not seen where automakers are specifying speed ratings for their models. But if so, I'm curious - can you identify any specific makes/models that do so? For newer cars, Tirerack identifies OEM tires and that would suffice as a 'minimum' I suppose albeit indirect or implied specification only. Over time I think you'll find fewer and fewer S and T tires land on cars as OEM tires going forward.
BASIC RECOMMENDATION: For any passenger vehicle, when possible, consider an H or better speed rated tire (which will generally be a stronger tire and will carry an A temp rating) from major recognized tire manufactures that are sold and serviced by local or chain tire shops. Tire size and pressures are usually found on door pillars of you vehicle.
There seems to be an assumption that a higher (speed) rated tires enjoy shorter stopping distances wet or dry as function of the speed rating. That isn't entirely accurate. Stopping distance is a function of the rubber compound (esp dry) and tread design (esp wet), not a directly function of the construction of the tire. If you see a correlation in test data - it is just that, a correlation. By coincidence or design, higher speed rated tires do tend towards softer compounds. But softer compounds in and of themselves do not yield a higher speed rating. It does yield better adhesion.
If you are interested in stronger (safer) tires: Look at the speed rating (with H being the minimal cutoff where possible).
If you are interested in shorter stopping distances: Look at the compound (the biggest difference between summer compounds vs all-season compounds).
Tread designs offer a direct impact on WET braking. More R&D is almost certainly put into H and above tires. I really haven't noticed much if any change in the S and T tires still on the market today from decades ago.
There seems to be an assumption that lower rated tires last longer. Again, this is more of a function of harder rubber compounds favored for cheaper S and T tires. For longevity don't look at the speed rating, look at the treadwear rating. If for example you have an S or T tire with a 400 treadwear and an H+ tire with a 400 from the same manufacturer... guess what? They will last the same. a 300 treadwear rated tire will last abou 75% the life of a 400 treadwear rated tire. And so on. Cross brand treadwear ratings aren't technically identical but IMHO they are close enough, say within 5% of each if we're talking major brands. (Personally I like tires in the mid to low 300s for general/aggressive driving or even an occasional on-course jaunt but I recognize most folks prefer longevity over adhesion)
I've not seen where automakers are specifying speed ratings for their models. But if so, I'm curious - can you identify any specific makes/models that do so? For newer cars, Tirerack identifies OEM tires and that would suffice as a 'minimum' I suppose albeit indirect or implied specification only. Over time I think you'll find fewer and fewer S and T tires land on cars as OEM tires going forward.
BASIC RECOMMENDATION: For any passenger vehicle, when possible, consider an H or better speed rated tire (which will generally be a stronger tire and will carry an A temp rating) from major recognized tire manufactures that are sold and serviced by local or chain tire shops. Tire size and pressures are usually found on door pillars of you vehicle.
Statistics: Posted by PGR — Sat Jan 04, 2025 3:59 pm — Replies 68 — Views 3595