Why is it that the load index for the TL-P (16 inch tire) is 91V, and the TL-S (17 inch tire) is 93V? I am sure the engine weighs the same between the two cars, so I don't see how the two cars require different load capacities. And I would not think that the rim sizes would have anything to do with it, but I could be wrong.

 

They probably chose 215/50/17 and didn't put the load rating as a priority as long as it was the same or higher than the 91 on the P...




I went 95 Reinforced on my 235/40/18 just in case.

 

The 17" tires are reinforced, meaning that they are built extra stout for increased load capability. A typical 215-50-17 tire has a 89 to 92 index.

 

Well we all know that a tire should be replaced with the same speed rating and load index (at a minimum). So with that being said, would u still have to use a 93V rated tire for a 215-50-17 tire on a TL-P (which is slated for a 91V rated tire)? Hmm . . .

 

The 16's have a load index of 91 with recommended pressure of 32 psi, it will have a load capacity of 555KG.

The 17's have a load index of 93 (extra load or reinforced tire) with a recommended pressure of 32 psi, it will have a load capacity of 520KG.

Therefore, the 17's have a lesser load capacity than the 16's. Thus, 35 psi would have been the appropriate tire pressure to meet or exceed the load capacity of 555KG. The manufacturer went with a lower tire pressure for comfort.

Therefore, it would be okay to be in the load capacity range of 520KG to 555KG.

Use 91 load index as the reference.

88 load index is fine too, as long as the tire pressure is increased between 4 psi to 10 psi (depending on standard load or extra load).

I am usually between 39 psi and 42 psi on 225/35/19 reinforced tire with a load index of 88 which would be between the range of 530KG to 560KG


Reference: The European Tyre and Rim Technical Organisation (ETRTO)

 

It is due to tl-s has firmer suspensions and lower profile tires. I don't think the weight was the factor of the increase 93v rating.