Maximum back spacing on 15x8 wheel with 33x12.5?

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For a 4" lift, what is the maximum backspacing that can be run with 33x12.5" tires? I want more backspacing to have less tire sticking out from under the wider rubicon/sahara flares. What typically limits it? what rubs first on both the front and rear?

I know that the norm is 3.75" or 4", but wondering if we can go 4.5" or 5"

thanks
 
You could run 5" if you wanted. The kicker would be that you'd need to adjust your steering stops out more, so you'd effectively decrease your turning radius.

I ran 285/75R16 tires which come out to 32.8x11.2 on the factory Rubicon Moab wheels, which have 5.25" backspacing. They barely, barely rubbed on full lock with the steering wheel.

So if you added an extra 1.3" to that (to make it 12.5") but then took away .25" of backspacing, you'd have 1.1" roughly. Which means you'd definitely have rubbing.

My suggestion is stick with a 3.75" to 4" backspace and put Rubicon flares on it, which stick out 1" wider than non-Rubicon flares. This will cover the tire almost entirely.
 
Thanks Chris, we have sahara flares, so that is already in the plan. Do you have any good pics that you could post of how your 285/75/16's fit with the 5.25" BS and rubi flares? I want to see where they are as a starting point. thanks
 
just out of curiosity, where to the tires rub on the inside? on the control arms? what about the rear?
 
The tires would probably rub on the front sway bar and on lower control arms in the front. not sure in the rear, probably wouldn't rub at all though.
 
Jamesval035 said:
The tires would probably rub on the front sway bar and on lower control arms in the front. not sure in the rear, probably wouldn't rub at all though.
Click to expand...

This is correct. They won't rub in the rear most likely, it's usually just the front.
 
For reference, the following photo shows 315/75R16 tires (34.5" diameter, 11.9" wide) on 8" wheels with 4.5" backspacing and Rubicon fender flares. Rubbing on the lower control arms was totally eliminated by adding one washer on each side to the steering stops.

A 12.5" wide tire would rub more with 4.5" backspacing than a 11.9" wide tire, but 4" backspacing rather than 4.5" should eliminate the issue which is why I typically recommend 4" backspacing for 8" wide wheels.

Mr. Bills Jeep 2.jpg
 
Thanks, that helps alot. I am finding most 15x8 wheel have a 3.75" BS. So that would push the wheel out from where yours is by 3/4", and on top of that the tire is .6" wider (pushing the outer side out another .3"). So a 12.5" tire on a 3.75" BS would stick out 1.1" more than your pic. Too much for us I think. With the MA state inspections, I don't think I want it out much more than yours.

There are much better BS options in 16" wheels and also 11.2 and 11.6" tire width options, so I may go that route despite the D & E load ranges...
 
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