What offset and back spacing should I get on my wheels?

[jaydenyates]

I just bought a Jeep gladiator and am Planning on putting some Nito Ridge 37x13.5x18 with a 4 inch lift. What is a good offset and backspacing where I won't have any rubbing?

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[Dougstdig]

You didn’t ask, but I’ll say it anyway. I recommend a 17” wheel. It will allow you to have a larger foot print while off road and be cheaper for the wheel and tire.

If you went with the 17, I just got a response from Ozark Overland Adventures and he indicated he’s running a +20
(EDITED) on a 17x9 Vision with 38x13.5”. He’s running a Clayton 3.5 overland+ kit and gets a touch of rubbing so may upgrade to the 4.5 springs out back (haven’t been released yet), which you shouldn’t have an issue running 37’s. The poke seems just about perfect.

 

[Rahkmalla]

-12 on [...] 38x13.5”.

The poke seems just about perfect.

I honestly don't see how this could possibly be a 13.5 tire at -12. I run a 12.4 wide tire at +6 and I have significantly more poke than that.

If you check my Build Thread you'll see what 12.4s at +6 with xr fender flare extensions look like. 13.5s at -12 should be sticking out 1.21 inches more than mine.

 

[Jeepasaurus_Rex]

It really depends on how you set up your bumpstops. I'm running 40x13.5x17 with a 0 offset wheel and don't have any rubbing

 

[Lunentucker]

0 to +6

 

[Dougstdig]

I honestly don't see how this could possibly be a 13.5 tire at -12. I run a 12.4 wide tire at +6 and I have significantly more poke than that.

If you check my Build Thread you'll see what 12.4s at +6 with xr fender flare extensions look like. 13.5s at -12 should be sticking out 1.21 inches more than mine.

I’ve looked up the rim on the manufacturers site. I think it comes in -12 and -35. Keep in mind this is a 9 inch wide rim not an 8.5 that you can get by running on 12.5 wide tire.

 

[kevman65]

OP, ask the manufacturer of the lift you plan on using this exact question. They know better than anybody on the internet because "WE" don't know what lift you're getting so "WE" don't know the specs. The manufacturer knows all the specs for their lift.

 

[bleda2002]

4.5 to 4.75 of backspace is in the ideal range.

 

[Lunentucker]

4.5 to 4.75 of backspace is in the ideal range.

On what width?

 

[Dougstdig]

On what width?

OP previously indicated 37x13.5 on 18. He didn’t indicate a wheel width.

 

[Lunentucker]

OP previously indicated 37x13.5 on 18. He didn’t indicate a wheel width.

That's what I was thinking.
Offset is relevant to width. Width is relevant to offset.

 

[bleda2002]

On what width?

Backspace is measured from the mounting surface to the back edge of the rim. 4.75-4.5 is ideal in that it will let you clear over 40's on rubicon axles with out rubbing on the control arms or fenders when turning or flexing (assuming you get the bump stop height right). Want more poke, go 17x9 or 17x10, less poke go 17x8 or 17x8.5

The offset to achieve that 4.5-4.75 of course depends on rim width, i've found that 0mm offset on 8.5 wheels giving you that 4.75" backspacing seems to be a real sweet spot between minimal poke, and plenty of tire clearance.

 

[Dougstdig]

…been posted numerous times. I saved it for these posts.

-12 on a 9 inch rim is the equivalent of a -6 on an 8 1/2 inch rim, which is the widest I would contemplate going. ATV wheels or a +25 and they run Tomašić 35 and 37 inch tires. Mopar performance wheels are a +12 so ideally I’d like to be around there on a 12 1/2 inch wide tire.

For reference the stock wheels on my Rubicon and the stock wheels on a buddy of mines sport S JLU are both +44 to +45. So I’m really not surprised with the rubbing.

 

[Wheelin98TJ]

OP, ask the manufacturer of the lift you plan on using this exact question. They know better than anybody on the internet because "WE" don't know what lift you're getting so "WE" don't know the specs. The manufacturer knows all the specs for their lift.

The better lift manufacturers know, but not all of them do. Some of them don’t have as much testing as the experience on this forum. Lots of different setups when it comes to tire width, wheel offset, axle width, fenders, model year changes to inner fenders, etc.

 

[Lunentucker]

That's a great resource and good reference.

I'm a pokaphobic, and don't want any more sticking out past the fenders than is necessary.

Obviously, the more you move the center out from the hub the more you move the inside edge AND the outside edge outward.

I guess the industry safety net lazily hovers around 0 offset (4.5 backspace on a 9 inch rim). That gives wheel makers more room to not rub and avoid complaints and issues from undereducated consumers, but MAN!, I hate unnecessary poke.
Mud, snow, water, rocks all get more working room to make life more miserable than it needs to be.

My stock Mojave rims are +37.17 offset and they keep things tucked away nicely on 12.5" 35's.
My formula for aftermarket wheels is to add and an inch to the rim width (stock is 7.5) , which will likely equate to about 1.5" inches on the tire as the 12.5 footprint relaxes a bit more.
So 38 mm increase /2 = about 19 mm from my original 37 to keep things pretty much where they were on the inside and rub free. +12 to 18 mm on my rig would be great.
0 offset is way more than needed.

If ALL I was going to do was drive off-road, it wouldn't be an issue, and some extra tire sticking out can keep the body off of side obstacles like trees and rock. Of course, they can also restrict you in super tight spaces.

Here's a great link to shop rims by offset (backspace) and more criteria
Custom Offsets - Gladiator

Here's a great resource to help visualize changes in rim size, offset, and tire size.
Tiresize.com

OP, beyond what you've read here, surf the other threads and galleries for setups similar to yours and see what you like and what you don't like.
Don't rush into more poke than you need or ultimately want.
Your factory offset is stamped on the inside of the rims.
Ultimately, that's your starting reference.

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