Your options are pretty simple. You’re already running the widest tire your combination will allow without any changes.
So if you want to run wider tires you’ll need to add at least one of the following
- Wheel spacers
- New rims with less backspace than your current rims
- A 1/2” spring offset
- A wider rear axle
Now a wheel spacer will help and should be pretty cheap. They’ll need to be at least 5mm thick to account for the extra tire width, maybe more. The only complication will be running out of threads on the stud if you go with too much spacer.
It looks like you have a decent amount of backspace on your current rims. Dusters have enough room to run 275’s on 8” rims with the right backspace, yours are too close to the springs for anything close to that. So if you bought rims with say a 1/2” less backspace than you’ve got now you could run 255’s no problem.
A 1/2” spring offset from DoctorDiff would also solve your issue, but, you’d have to remove the spring perches and weld on a new set a 1/2” inboard. If you can weld and do that yourself it would probably be on par with new rims cost-wise, but more work.
Last is a wider axle. It looks like you already have the 5x4.5” bolt pattern wheels? If that’s a 7.25” rear axle in there, you might want to consider an A-body 8 3/4 which will be wider (and lots more expensive!!!). If that’s an 8.25” in there, then just do one of the first three options. Both the 7.25” and 8.25” rear axles are narrower than the A-body 8 3/4’s were, which might explain why you’ve got so little room. But the 8.25” is plenty strong, so easier to deal with the issue one of the other ways.
