Novak Conversions Jeep Wrangler TJ engine mounts

Pics of 3.75 backspacing with 10.5 tyres (ideally 31")

Roger Dunning

Roger Dunning

TJ Enthusiast
Original poster
Joined
May 9, 2025
Messages
111
Location
Chichester, West Sussex, UK
I'm looking at these American Racing Baja's. 15x8 with 3.75 backspacing. They would be shod with 31/10.5/R15 AT tyres. I am trying to understand backspacing and I want to see pictures (ideally from the front or back) of 3.75 offset tyres with 10.5's so that I can see how far they stick out. I believe I have the larger fenders that were on the sahara and rubicon.
Thanks!

IMG20250920165601.jpg
 
Last edited:
Backspacing is the distance from the inside edge to the wheel mounting surface.

1761319584603.jpeg


Rubicon and Shara flares measure 4.5” width.
 
You currently have 5.25" BS with a 7" wheel, and I am assuming the new wheels are 15x8, so they will stick out roughly 2.5" or 63MM per side, plus the additional section width of the wider tire.

It will be noticeable how far they stick out vs now. I'd recommend less BS or a narrower wheel. American Racing offers Baja in 15x8 with 5.29" BS....I'd recommend that one instead of 3.75.

If you are looking at 15x7 3.75" BS, then that changes what I said a bit.
 
machoheadgames said:
You currently have 5.25" BS with a 7" wheel, and I am assuming the new wheels are 15x8, so they will stick out roughly 2.5" or 63MM per side, plus the additional section width of the wider tire.

It will be noticeable how far they stick out vs now. I'd recommend less BS or a narrower wheel. American Racing offers Baja in 15x8 with 5.29" BS....I'd recommend that one instead of 3.75.

If you are looking at 15x7 3.75" BS, then that changes what I said a bit.
Click to expand...

You're right, I should amend that. It is 15x8. Ideally I want them to stick out a little. It's purely for looks/stance. I just don't want it to be too far. I did a measure up and I think it works but just keen to try to see it in practice. I'm in the UK and it will only be driven on the road or light trails.
 
Roger Dunning said:
Some great pics there. Looks like you have some great trails wherever you are. Very similar wheels to what I’m planning too. It looks like they maybe stick out an inch or so?
Click to expand...

It will be more than an inch. Simple math dictates that. The edge of the wheel will be 2.5" further out than what you currently have stock. Wheel being 1" wider and backspacing being 1.5" additional makes that certain. How much actual tread sticks out depends on the construction of the tire.
 
Roger Dunning said:
Some great pics there. Looks like you have some great trails wherever you are. Very similar wheels to what I’m planning too. It looks like they maybe stick out an inch or so?
Click to expand...

Thanks; lots of great trails here in AZ. As others have mentioned, variations in tire construction can come into play, as can inflation. I'd say ~1.5" from directly below the fender flare lip to the edge of the tread block is a good general assumption.
 

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