What is the maximum backspacing allowable on the front of a stock suspension given 18" wheels?
I'm in the process of re-doing my duster. I just picked up a 68-69 B Body dana 60 that I plan on running. It has 42" perches, and was supposed to have been under an a body. Do you think it was run with an offset kit?
I like the 07-09 SVT Mustang wheels - 18x9.5. 45mm offset, 7.125" backspacing.
Currently I have 275/60-15 in the back and 235/60-15 in the front. I rub a little on the fender lip on both front and rear under extreme circumstances. I've calculated ~1/4" negative offset on the back and ~1/4" positive offset in the front (15x8 rear 15x7 front, both ~4 1/4 backspacing).
This wheel should be perfect in the rear - 45mm offset = 1.75" offset, which is 2" different than current. Given the 1.5" added axle width, that should put me at .5" centerline moved inward. I don't know how much room I have with the stock spring location, but I'm considering the offset spring relocation (since the perches are already ~.5" in on a side).
The front is where I'm concerned - can I run a 7.125" backspace with the stock suspension on an 18" rim? I saw somewhere there was a limit given - I lost the post and havent been able to find it again. My tire width was 9.5" with the 235 and a 275/40/18 would be 10.9", or adding .7 inches on each side. The centerline would move inward by 1.5" of it's current location, and then be offset by the .7" of added tire width on that side. So, the tire would be .8" inside of where it is now, which would be good to get it further away from the fender with the more upright-ness of the lower profile tires.
Thanks!
I'm in the process of re-doing my duster. I just picked up a 68-69 B Body dana 60 that I plan on running. It has 42" perches, and was supposed to have been under an a body. Do you think it was run with an offset kit?
I like the 07-09 SVT Mustang wheels - 18x9.5. 45mm offset, 7.125" backspacing.
Currently I have 275/60-15 in the back and 235/60-15 in the front. I rub a little on the fender lip on both front and rear under extreme circumstances. I've calculated ~1/4" negative offset on the back and ~1/4" positive offset in the front (15x8 rear 15x7 front, both ~4 1/4 backspacing).
This wheel should be perfect in the rear - 45mm offset = 1.75" offset, which is 2" different than current. Given the 1.5" added axle width, that should put me at .5" centerline moved inward. I don't know how much room I have with the stock spring location, but I'm considering the offset spring relocation (since the perches are already ~.5" in on a side).
The front is where I'm concerned - can I run a 7.125" backspace with the stock suspension on an 18" rim? I saw somewhere there was a limit given - I lost the post and havent been able to find it again. My tire width was 9.5" with the 235 and a 275/40/18 would be 10.9", or adding .7 inches on each side. The centerline would move inward by 1.5" of it's current location, and then be offset by the .7" of added tire width on that side. So, the tire would be .8" inside of where it is now, which would be good to get it further away from the fender with the more upright-ness of the lower profile tires.
Thanks!