Tire Speed Rating Question
I'm posting this here because the speed rating of a tire seems to me to cross all lines/types of vehicles. Reading up on warranty issues/questions just now, I came across the following language ...
Forum Discussion
CapriRacer wrote:
I wonder if this is a difference in interpretation.
On the Pickup page, they don't specifically mention a maximum speed. It is only implied by the speed rating.
On the RV page, it is explicit. I wonder if Michelin feels the need to be explicit for RV's because of the fact that RV's tend to be use infrequently and tend to be loaded up pretty much all the time.
I have read that the speed index is a result of a laboratory certified test process.
Using the Q=99mph for example, means that the tire has passed 99mph tests. I don't believe that means it will run 99mph for 80k miles on a truck or RV.
Prudence and common sense suggests to run well under 99mph to experience the expected use of the tire. I believe the Michelin's 75mph limit is simply a warranty issue. In fact, it speaks well of them to state the 75mph while other mfgrs give little such guidance.
Especially consider the ST tire with the 65mph rating. Was it easy to find that out while researching tires, or was that critical fact hidden in the fine print? What do we really expect to happen when we run them at max load and psi, and 65mph?
As an analogy, my car engine red lines at 6500rpm, but I don't expect that to mean I can run it at 6499rpm for 100k miles.
HTH;
John
