CS Legal Wheel
 

I'm new to autocross but I'm perusing different stores to see what sort of options there are if I wanted to get a second set of wheels for my summer tires. From what I've read I need to keep the stock size/width, and also keep relatively close to the original offset of the wheels. That said, does that mean something like this would work?

http://www.machiii.net/index.php/whe...t-version.html

They'd be a bit lighter than the stock wheels and hopefully let me stay in the stock class. The only question is if there's some additional rule that I'm overlooking that would make these wheels bump me up or something.

Thanks!

Ya these would work they look nice. You can go from a 17x7 +48 to a 17x7 +42 to help widen the track of the car just a tad.

How much does the 6mm wider offset really effect performance?

I have read talk that narrower is better for slaloms, but since 6mm wider isn't even flush with the body, would it really make the car "wider"?

What are the real world benefits are there to a 6mm wider offset?
Fit wider tires, maybe?

Narrower overall is better for the reason of total track width squeezing through features. The reason for 6mm more would be tire clearance to the front struts. I believe 42mm offset with 225-235mm tires shouldn't really extend past the bodywork considering the rear is wider. So the +42 is a good idea if you are running 245 or bigger tires, but for most the +48 I would guess is fine.

The 5zigen FN01R-C was one of the wheels I was looking at when looking for stock class wheels but I wasn't sure if 245 Hoosiers would fit with the +48 rim. I had friends that ran them years ago and always liked them. Can't beat the price either.

From my test fitting I do think a 245 Hoosier would fit in the front even with a +48 rim. It's going to be really close but I think it would fit and if it didn't a 3mm spacer would probably work. With a +42 rim and a 245/40/17 Hoosier A6 there is probably a little under 1/2" between the tire and the front spring perch. 6mm is less than 1/4".

With a +42 rim the 245 Hoosiers still fit within the front fender.

Noob stock class question here:

Is there any benefit (performance wise) to staying with the narrower offset (tire track narrower than body width)? No matter how narrow the tire track is, the body of the car still has to navigate the cones, right?

Other than that, I imagine that a wider offset would negatively effect turn-in response (a bit), but add more transition and steady state stability, right?

So I guess you would ideally want to go wide enough to not effect overall vehicle width, correct?

6mm really isn't going to change much of anything. As long as you aren't wider than the body, like you said which can hit cones too.

Are they any lighter used or OEM Subaru options out there?

I'm waiting on the Enkeis to become available, but I wouldn't mind having a spare set.

There are a couple that are lighter than stock but the offset is +50. I'm waiting for the RPF1 in 17x7 +42 for $219ea in to be released in October before I decided.

i'm using the Koesei wheels with the +50 offset and 1/4" spacers in the front.
the Hoosier 245 A6 tires without the spacers were just a little too close to the struts
for my liking.

if i get the RPF1 wheels i may also need to get longer wheel studs as the extra 2mm
offset may not allow for enough thread contact to keep the nuts secure.

You should not need longer studs. It should have the hub of the wheel machined so that isn't necessary as it is with other wheels.

I'm looking at the same wheel! I heard from a friend that the newer productions of RPF1 are supposed to be more rigid as well. Supposedly they did a quiet design upgrade, but it only applies to newer sizes and production lots...

The Tire Rack RPF1 in 17x7 +42 seems to be the best available "bang for buck" wheel I've found so far.

That is my plan right now, but I'd be open to something from Team Dynamics, 949 Racing, or anything else.

I was looking at older 17x7 OZ Superleggeras from early WRXs that might work with (or without) hubcentric rings, though the offset was still +48.

Man I wish 949 would come out with a Stock class legal wheel.
I love their dual valve set-up!! Don't ever see it happening though...