quick question?? wheel fitment

[oldman14ss]

what i have 75 camaro/ 72 camaro front end. CPP upper and lower tubular control arms front stock coil springs. rear strange dana 60 factory specs housing width. ive heated and beat the seat belt humps in. looks pretty good if i do say so myself. question?? i want to put on 18x9 inch wheels all the way around so i can rotate from front to back. make it as they say a SQUARE set up. what BACKSPACING do i use 4.50 inches? 5.0 inches? 5.5 inches? was wanting to run 275/40/18 tires? no wider. do they make a 275/35/18? thanks ahead of time. all you all knowing please help!

 

[djorgensen3]

I have 15x10 with 5.5" backspace on the rear of my 71 and the seatbelt hump is not bashed in and can barely fit a pinky between them. I can't go wider without doing that or mini-tubbing. Hope that helps a little bit. I don't have any help on the front because my fronts are skinnies.

 

[oldman14ss]

Thanks that's 50% of the problem solved. What is the diameter?0

 

[djorgensen3]

Oh...I'm running 275/60-15 on the rear if thats what you're asking.

 

[oldman14ss]

Yes I'll look up the diameter thanks

 

[djorgensen3]

Its about a 28" diameter tire.

 

[oldman14ss]

Thanks now my conundrum is front wheel fitment . Might call speedway tomorrow, summit etc.

 

[G72Zed]

First you need to make sure of the front track width, did it change with the new parts installed.

The issue with the front can be based on the ride height you want, a 275 front tire is wide for our cars and can pose issue on max turn in, and most manufacturers ask for a rim range of 9-11"

At 9" rims, you need approx. 5" BS and go from there. The dia. is approx. 25.6 for a 275/35/18 and widely available, Kumho PS91 as an example.

If you have a lowered stance all around, a 255/40/18 with 5.5 bs may be a good choice.

Lots of good info on this site, but in the end, you need to measure and test fit the actual rims/tire to make sure everything works in all four corners.

 

[oldman14ss]

Thanks, that's what I'm afraid of buying something that won't work. Stock ride height with new Detroit springs is what I have.

 

[oldman14ss]

Turn in was what I'm afraid of, actually both directions.