The question of rear tire size keeps coming up with different answers all over the map. I finally crawled under my car a few minutes ago and did some measuring.
The available space (not considering the shock and mount intrusion) from the inside of the lip to the inner wheelhouse on my car is right at 11-3/4". Assuming that my car is "normal and stock" with these dimensions - and allow a little clearance on each side and that says that the maximum tire you can run inside the wheelwell without rubbing is an 11" sidewall width which generally leaves you with a 10" tread width.
Anybody disagree or have different measurements?
On my car I have 8" American Torque Thrust II rims in the back and 255/45/17" BFG Comp T/A tires which gives me 9" tread width and a 10" sidewall width. I have about 1/2" clearance to the the lip and about 1-1/2" inside.
However, because my car is lowered 2" I now only have 3/4" between the shock bracket and the edge of the wheel. Unless I relocate my shocks inside the springs (a definite possibility) I can't go any wider.
If I do move the shocks - the next step in TT2 wheels I believe is 9-1/2" which would fit with the proper b/s - maybe 5-1/4 or 5-1/2"?? . My total inside available space is just about 11-3/4" inches - so I could reasonably go to an 11" sidewall tire and still not rub with the right backspacing. You could probably squeeze in a little more but I'm not up for clearance problems. The BFG site says their 275/40/17 Comp T/A has an 11" section width.
So - computing all that means that the biggest setup I can squeeze inside the wheelwells of my lowered ride are 9-1/2" wheels with 5-1/2" BS and BFG Comp T/As @ 275/40/17" and that's if I move the shocks.
Any ideas - thoughts - angles I've missed? Has anyone moved their shocks? Anyone running these sizes on a lowered car?
'69 400SB, Richmond 5-speed; '99 HD Road King Classic