Enkei 17x9 or 17x9.5?

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Enkei 17x9 or 17x9.5?

Postby JeffJ234 » Tue May 24, 2016 2:46 pm

I'm looking at getting a set of RPF1's and wondering whether there is any benefit in going with 9.5 width (38mm offset) vs. 9" (45mm offset). My use will be HPDE and possibly TT. Tracks are Sears Point, Laguna Seca, and Thunderhill. I do not plan to do a big brake kit in the future. Tires will likely be something like the Nitto NT01 in 255/40-17.

The main benefit I see with the 9.5" width is being able to run a slightly wider tire should that ever be desired. It may help turn-in on some corners. On the other hand, the 9" will be (slightly) lighter, less resistance, and it costs less. Any thoughts appreciated!
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Re: Enkei 17x9 or 17x9.5?

Postby Brian » Wed May 25, 2016 9:15 am

That 255mm is a 10 inch wide tire, so 9.5 wide will be quite a bit faster than 9 inch wide...and 10 inch would be even faster. The more the tire is supported, the better it can do everything, sharper turn-in, contact patch staying stuck to the ground, etc. Thus, for track and autocross the more rim support the better. I consistently race a 255mm tire on 10 inch Enkei 17x10 and 6UL wheels.

I will mention the downsides for real world driving, where max support of tire with wide rim means less ride quality and more chance of curb rash. So if driving the combo every day then the lighter 17x9 has some real attraction.
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Re: Enkei 17x9 or 17x9.5?

Postby JeffJ234 » Wed May 25, 2016 7:17 pm

Thanks! For now I want to avoid fender rolling. Do you know if the 17x9.5 with 245/40 or 255/40 fit in the stock fenders?
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Re: Enkei 17x9 or 17x9.5?

Postby Brian » Thu May 26, 2016 6:50 am

Must consider offset too. The 38mm offset of the 9.5 will require fender rolled up flat for 255mm.

The 45mm of 17x9 and 18x9.5 can get the 255mm in much easier.
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Re: Enkei 17x9 or 17x9.5?

Postby JeffJ234 » Thu May 26, 2016 10:21 am

Thanks, got it. Really appreciate your input.
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