C3 wheel offest/backspace question
Pro
Joined: Sep 2013
Posts: 657
Likes: 99
From: Slidell Louisiana
I wasn't the one to reply to Kubs that was someone else. So let me ask you this. On the 17x9.5 with 4.5 BS would be different then the 15x8 with the 4.5 BS since it's 1.5" wider right? So I could just judge it based off that it will be not as far out basically 1.5"?
Im curious if I need to do a small spacer like your are running or if a 1" hubcentric adapter would be too wide.
Im curious if I need to do a small spacer like your are running or if a 1" hubcentric adapter would be too wide.
Thread Starter
Advanced
Joined: Jul 2016
Posts: 64
Likes: 6
From: Walker Louisiana
My mistake. I was on my phone earlier. The only concern is the backspace as that will determine if you will make contact with the E-brake line. The additional width of the wheel (be it either a 9.5, 10 or 11 inch wheel will be out towards the fender. 9.5 inch minus 4.5 inch of B.S. just gives you 5 inches out towards the fender. You can probably do a 4.5 inch B.S. with like a 1/4 inch spacer and clear everything. But every car is different. I see people running 4.5 inch B.S. on a 15 inch wheel and clear everything. I could not do it on my car from some reason.
Le Mans Master
Joined: Oct 2007
Posts: 9,700
Likes: 3,469
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
I would say they are slightly stretched if any, but the sidewalls are pretty even with the lip of the wheel.
They may look wider because putting a smaller tire on a wider wheel (to a small degree) helps bring the corners of the tread up and flattens the footprint. This also changes the angle of where the body plys go under the belt known as the "attack angle". This will help stiffen the sidewall and give better steering response, and the flatter footprint allows for more lateral traction.
Drifting
Joined: Aug 2015
Posts: 1,939
Likes: 477
From: NSW, Australia
C3 of Year Finalist (track prepared) 2019
So are you saying that you have the 275s on your stock wheels fitted to the car right now? If so, a 15x8 with 4.5" backspace and a 1/2" spacer will fit identically to your current wheels (you'll probably need longer studs and want nice spacers). As will a 15x8 with a 5.5" backspace and 1.5" bolt on spacers/adaptors - however keep in mind that these will also have less dish to the rim, which may or may not be the appearance you are looking for.
Thread Starter
Advanced
Joined: Jul 2016
Posts: 64
Likes: 6
From: Walker Louisiana
So are you saying that you have the 275s on your stock wheels fitted to the car right now? If so, a 15x8 with 4.5" backspace and a 1/2" spacer will fit identically to your current wheels (you'll probably need longer studs and want nice spacers). As will a 15x8 with a 5.5" backspace and 1.5" bolt on spacers/adaptors - however keep in mind that these will also have less dish to the rim, which may or may not be the appearance you are looking for.
Le Mans Master
Joined: Oct 2007
Posts: 9,700
Likes: 3,469
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
That would put the wheel 0.5" closer inside the body than in the picture I posted. Its up to you if that still sticks out too much or not. Shouldn't have any clearance issues on the inside part of the wheel.
Last edited by Kubs; Jul 21, 2016 at 11:13 AM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Advanced
Joined: Jul 2016
Posts: 64
Likes: 6
From: Walker Louisiana
Hmm I may run that. I wonder if running a 1" adapter would be better as far as having the tire not as far out the body. Think I wouldn't have clearance issues in the back side?
Le Mans Master
Joined: Oct 2007
Posts: 9,700
Likes: 3,469
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
At least on my car, the stock wheels with 4" of backspacing put the wheel really really close to the spring and parking brake cable. I don't think there was enough room to go farther in. However, places like Van Steel make shorter springs, and it would be real easy to move the parking brake cable bracket.
Drifting
Joined: Aug 2015
Posts: 1,939
Likes: 477
From: NSW, Australia
C3 of Year Finalist (track prepared) 2019
Thread Starter
Advanced
Joined: Jul 2016
Posts: 64
Likes: 6
From: Walker Louisiana
Ill measure it tomorrow. But looks like the passenger rear tire is out farther then the driver's side. Def noticeable. Not sure why though. I will get some pics of it as well.
Last edited by Five Oh; Jul 22, 2016 at 04:47 AM.