What is the lap time difference between 17x8 and 17x9

[hpde_addict]

Originally Posted by OkieSnuffBox

Forgive me if I misunderstood you're OP, are you asking about the difference of a 245 on either an 8" or a 9", but also changing the tire width as well? Others brought in the size difference, so I wanted to make sure I'm clear on what YOU are asking.

In the Miata world, we run very wide wheels compared to tire size. The speed difference is marginal, but the feel is better. For EHP and Comps, 205 goes on an 8", 225 on a 9", 245 on a 10".

Testing has showed the 225 won't be much slower, if at all on an 8 vs a 9", but the feel consistency is better so it's typically a touch easier to get "all of it" all the time.

I had assumed 8" -> 225 and 9" -> 245, since those are the combinations I saw recommended the most.

Good point about the tire width. From a quick look, tire weight is much higher than wheel weight and is located on the outermost radius, so tire width will have the greatest impact on acceleration.