Wheel spacing question for those with 3.5-4.5" lifts with tires

Jerry Little

Jerry Little

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I have a question for those of you who have more knowledge on these jeeps tires and wheels. So I want to put a Rubicon Express Super Flex 3.5" lift kit. I would like to use a 18" wheel by 8 or 9" wide and a 285/65/18 tire as I look the look of this set up. It is 32.6" high. 11.22" wide. What kind of back spacing variance can I use and offset. can those of you who have a 3.5-4" lift share the backspace and offset you have. Thank you for your info.
 
Just a note - while you might like the look of an 18" wheel, they look odd on a TJ with the smaller wheel well opening, plus you will be limiting the selection of tires in that size. If you do not want a 15" or 16" wheel, IMO you'd be better off with a 17" wheel than 18". There's tons of tires now in that size.

I know this does not answer your question, just throwing that out there...but if you look in the FAQ section, there's threads about this very subject.

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glwood said:
Just a note - while you might like the look of an 18" wheel, they look odd on a TJ with the smaller wheel well opening, plus you will be limiting the selection of tires in that size. If you do not want a 15" or 16" wheel, IMO you'd be better off with a 17" wheel than 18". There's tons of tires now in that size.

I know this does not answer your question, just throwing that out there...but if you look in the FAQ section, there's threads about this very subject.
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glwood, thank you for this info. You have me thinking on that now this is what I needed. I will consider 17" instead now. how about a 6.07 backspace? will that work? 40mm offset what is stock offset and backspace?
 
You really only need be concerned about backspacing, don't bother with the offset. You simply need enough to keep whatever tires you get from rubbing at full steering lock. And, an 8" wide wheel will work with the size tire you want. I run stock 16" wheels on my TJR, so I will let those who have gone aftermarket on wheels to chime in.

I'm pretty sure a 285/70/17 will be equal to the 32.8" tire you referenced previously.
 
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Jerry Little said:
glwood, thank you for this info. You have me thinking on that now this is what I needed. I will consider 17" instead now. how about a 6.07 backspace? will that work? 40mm offset what is stock offset and backspace?
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Stock backspacing is 5-5.25 depending on wheel. 6" with that wide of a wheel/tire combo is going to do some serious rubbing.
 
40mm offset is factory for the jk(well, 42mm), and too much for a TJ. However, when you add the adapter (1.25" thk is common) , you end up almost at the factory offset.

Offset and backspacing are different measurements for the same basic thing.
 
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backspace.gif

If you look at this diagram and think about it, the more backspacing you have on a rim, the closer it places the back of the tire to the frame. This becomes even more of an issue when turning the front tires. Seems like an awful lot of people on this forum run a 3.75" backspace on their aftermarket rims. Very popular.
 
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Jerry Little said:
How then would I know which back spacing will work? All back spacing 4.5" or more will work on all wheel combos no?
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With a 10+ inch wide tire you want something around 4" of backspace. 4.25-3.75 is a very common range of BS for a majority of wheels so you should be able to find something you like.
 
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