I also don't think that going to such a tall tire makes sense! 1 mph is something that is hard to create that much of an issue in the first place, so I would not change anything there! If your car would have DCT this would definitely not be an issue!

 

1.7" Taller tire also raises CG 0.85". Needs more low, not more high


Hah, on that note and pertaining to ST*, anyone look at the gearing on the new Camaro for STP? Stock tire is like 28" tall and the car does 8x in 2nd. But going to a 285/35/18 would drop CG by 2" and speed to mid 70s... Could you do it?! Would look ridiculous but probably be faster.

 

Unfortunately for the Evo X good info is hard to find…
I don’t think there is a perfect 10” wheel offset for the Evo X (without touching the fenders or rubbing somewhere) I will keep the 9.5” with spacers for now.
As much as I would like a few more MPHs on 2nd gear I agree, the 265/45 tire is too tall and probably not worth it.
So 265/35R18 on 9.5” wheels it is.

 

Why not just run the 18x10.5 rpf1 in +15? Those are what guys are fitting with much bigger tires. And the 265s shouldn't be stretched much if at all on the 10.5. I have a pic around somewhere of 255s on a 10" wheel and people have been running 245s on a 9.5" wheel for years.

 

That wheel will definitely fit a 10 w/ 265 no problem. We were fitting it on 315s with stock fenders 5 years ago.

 

Ran some numbers on 10" wheels on the IX:

My current setup is the 17x9.5" +38 RPF-1. No spacer rear, 20mm spacer up front. Clearance to the rear trailing arm is slim enough that when a tire shop used clip-on weights on the inside of the wheel (ignoring my request for stick-on only) they rubbed on the trailing arm under hard cornering. I could probably bring the wheel in 1mm if necessary, but that's about the limit.

The 18x10" +38 RPF-1 adds 6.35mm on the inside and 6.35mm on the outside of the wheel.

With a 5mm spacer, the wheel extends 1.35mm more toward the inside and 11.35mm more on the outside.

With a 6mm spacer, that's 0.35mm more on the inside and 12.35mm (1/2") on the outside.

Searching around, I've found a few posts from people running +38 offset and 5mm as well as 6mm spacers in the rear. The tough part is knowing just how much they massaged the fenders, because what most people would consider to be a mild pull is still outside of the STU rules.

I'll have to put a 17x9.5" wheel back on the car, compress the rear corner as much as I can and see if I have 1/2" of extra clearance to the fender without going past 2 degrees of camber. I'm kind of doubtful.

 

I used to run 18x10 +38 RPF1s w/ 5mm spacer with an STU legal roll. I'll dig around to see if I can find any photos.

 

What tires?

The thing that sucks about the 265 is that it's taller than the 285s a lot of the ASP/SM folks would have run. When in doubt, add spring I guess

 

That was on 285/30/18. So yes, it's a fair amount shorter than 265/35.

 

I've found a couple posts from people running the 275/35s on the 18x10 setup, which is of course even taller than the 265/35: https://www.evolutionm.net/forums/ev...l#post11209260 No shortage of front camber on that car though. Also no word on whether or not he had to pull those fenders.

EDIT: But then there are posts like this one that really make me question the whole 10" wide wheel setup: https://www.evolutionm.net/forums/ev...l#post11259615

 

Fair point but, directionally, the measurements did answer my question which was if the 265 offered the biggest contact patch and it does. I'm not really concerned with exactly what that contact patch is, which is what I think measuring on "realistic" wheels would offer.

 

nevermind...

 

Over the weekend I disconnected the rear sway bar, pulled the spring from a rear damper, mounted the 245/40R17 17x9.5" +38 setup and compressed everything all the way up in to the wheel well. There was more clearance than I expected on both sides of the wheel, and my fenders aren't even rolled completely flat yet.

The people running 285s 18x10" +38 RPF-1s use a 5-6mm spacers in the rear to keep the tire from rubbing on the trailing arm. After watching Dallas J's tire squirm video here: https://www.evolutionm.net/forums/mo...l#post11251317 I wouldn't be surprised if we could get away with a slightly smaller spacer on our 265-width tires for slightly more inboard clearance.

Thanks to RJones for pointing me in the right direction.

 

Thanks for the reminder of the wide tire thread. I forgot I had posted there years ago. My pics and setup are in the post linked below

https://www.evolutionm.net/forums/ev...ml#post9243843

 

18x10 +38 RPF-1s on order.

Probably should have just bought this instead: http://www.corvetteforum.com/forums/...post1591400645