2016 STU Discussion!
#16
Evolved Member
Since I have an Evo X, I am definitely going 265. Debating about getting 10” wheels or keep the 9.5” finding the perfect offset wheels could be an issue… thoughts?
Options 1) 265/35R18 & loose ~1 MPH in 2nd gear; fitment should be ok
Options 2) Rumors of 265/45R18 RE-71 R coming this year??? That size should make the 2nd gear better for me…but this tire may be around 1.7” taller than the stock size 245/40/18 so clearance up front could be an issue.
Options 1) 265/35R18 & loose ~1 MPH in 2nd gear; fitment should be ok
Options 2) Rumors of 265/45R18 RE-71 R coming this year??? That size should make the 2nd gear better for me…but this tire may be around 1.7” taller than the stock size 245/40/18 so clearance up front could be an issue.
#17
EvoM Guru
iTrader: (1)
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.
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.
#18
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.
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.
#19
EvoM Guru
iTrader: (1)
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.
#20
Evolved Member
iTrader: (5)
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.
#21
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.
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.
#25
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
#26
Evolving Member
iTrader: (11)
Just to stir the pot (while the RS is still up for sale.....) Wouldn't the PROPER measurements for our wacky usage be more meaningful if done on the proper wheel widths? 245s were commonly ran on a 9.5" in STU, not 8.5"... so measure that vs. the 255/265 on the wheel widths likely to be used for the class. Anyway, wishing all my boost-brothers a GREAT showing in 2016, still up in the air what will be the next axe to play with here, though I am certain it will scream track-day/time-attack as much as anything.
#28
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.
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.
#29
Evolved Member
iTrader: (5)
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
https://www.evolutionm.net/forums/ev...ml#post9243843
Last edited by RJones; Jan 25, 2016 at 05:37 PM.
#30
18x10 +38 RPF-1s on order.
Probably should have just bought this instead: http://www.corvetteforum.com/forums/...post1591400645
Probably should have just bought this instead: http://www.corvetteforum.com/forums/...post1591400645