17x7.5 or 17x8?
 

We are currently investigating building the d-12c in either a 17x7.5 or 17x8.0 application. Would like to see which would be the size with consideration for scca autocross? Thanks for everyones input.

17x7.5 +20

Personally, to keep a 17" D12C as light as possible (15-16 pound range) I'd prefer 17x7.5. If/when I do decide to go FI I would be looking to put 245/40's on the rear and I do believe that these would fit on a 7.5. Also, I would like to get a wheel with a +35 to +38 offset.

Oh, I'd like them as soon as possible please :)

Seriously, if you decide to pet these in production I'm all in.

wow. Actually 17x8 is pulling away from the 17x7.5... interesting!

for autocross wouldn't most people want 17x9 since 9inch is the max allowed for RWD STX?

RFP1's in 17x9 are hugely popular for that very reason.

I heard somewhere the closer to stock the better it handles.... my friend put 8's on and he wish he hadn't the suspension is choppier and heaver when carving the canyons.

I guess it depends what you are looking for.
I was looking for changing it out as cheaply as possible so just a thought..

Weight would have a greater effect on handling then a 1/2 inch greater rim width. Of course, all else being equal, an 8-inch rim will always weight more then a 7.5 inch rim of the same design.

17x9... no?

There's got to be more to it than that, IMO. Possibly:

1) Increased weight (as mentioned above)
2) Increased wheel diameter
3) Increased wheel offset
4) Increased tire width
5) Different tire compound

Or any combination of the above.

I have 17x8's (+45) with 225/45 Z2's and it drives like stock daily, and has WAY more grip when pushed. The only time it feels different than stock at low speeds is in bad pavement, it tramlines worse.

If it feels drastically worse than stock with 17x8's it's either in their head, the offset is wonky or they went with heavy wheels/tires and it feels clunky.

I think probably 17x8 is looking to be a fairly clear winner here.. ;)

If it's for autocross the only two sizes that matter are 17x7 (+42-54 offset only) or 17x9, any offset.

Anyone buying special wheels for autocross wants a Stock illegal and STX uncompetitive wheel. Build us a light 17x7 +42 that isn't ugly (looking at you, Convex RPF1!) and you'll sell to us in droves

That is interesting to know and we really appreciate the assistance. We would be considering all 3 sizes

17x9 in all styles!