Wheel backspacing

[TwistedCU]

Factory 15x7 aluminum wheels on my Jeep. What's the factory backspacing?

I see many aftermarket wheels have a different offset and stick out too far for my liking. I'm trying to find out what backspacing is the factory backspacing to keep them the way they are now - tucked neatly under the fenders.

 

[Inspector-Gadget]

:shock:

 

[hi_c]

Twisted,

I'm going on a guess, but it's an educated guess. I KNOW that it's more than 4. Probably not more than 5.5. If I had to place a bet on it, I'd go with 5".

How do I know? I had some aftermarkets that were 15x7 with a 4" backspacing and with 31x10.50 tires, they stuck out about an inch from the fender flare. I now have factory TJ rims with 33x10.50 (same width) and they don't stick out, at all. I did a google search in the middle of this paragraph and an amateur site said that TJ's have 5.5" of factory backspacing, but I can't be 100%. I would say that it's around 5". HTH.

C

 

[Craig]

Hey Inspector, I don't know if that picture is correct on measuring wheel backspacing. Maybe it's how it's measured in a wheel store, I don't know. I work in a wheel manufacturing plant and here's how it's done.... Picture the wheel sideways. The part that attaches to the vehicle (called the drumface) when in the exact center of the wheel is at nominal (zero offset). If you move the drumface more towards the outside face of the wheel, it will cause the wheel to move further under the vehicle. This is called positive offset. If you move the drumface more towards the back of the wheel, it will cause the wheel to stick further out the sides of the vehicle. This is called negative offset. You could do it by the picture but you'd have to mark the center of the wheel width and measure to the drumface.

 

[ecor]

Gadget is correct on measuring back space. The offset is measuredin positive an negative, that is what you are talking about craig. On a 15 x 8 rim a -12 mm offset is the same as a 3-3/4" backspacing. A -6mm is a 4" backspacing. and a neutral offset is a 4-1/4" backspacing. Stock TJ rims in a 15 x 8 canyon has a 5.5" backspacing, thats why they look like front wheel drive rims. Hope this helps The specs and ways to measure are straight from american racing.

 

[TwistedCU]

I think you guys are both right. I was told there was a difference between backspacing and offset. I think I know how to measure both now. Thanks.

Does anybody know the factory backspacing or offset for a stock 15x8 Jeep wheel????????????????????

I have a 15x7. It may (probably is) be slightly different.

 

[Craig]

Not too sure on what the stock offset is on a YJ or a TJ. As for what I was saying before, it just clicked in that you could measure the offset the way the picture shows. I'm just used to doing it on high tech machines that measure it down to microns and never thought of doing it this way. To do it the way the picture shows, you'd have to know exactly what the width of your rim is. For example if you have an 8" wide rim and the drumface was 4" in from it, then your wheel would be at nominal (zero offset). They may have other, different ways of measureing backspacing that I don't know of.
But now that I think of it, I may be confusing the way I'm used to doing it with the way wheel retailers may measure it. I can't figure out how you'd have 4" of backspacing on an 8" wide wheel unless the drumface was even with the inboard part of the rim. Must be two different ways of doing this.

 

[Inspector-Gadget]

:shock:

 

[Craig]

From the way I see it, backspacing and offset are the same thing. They both measure how far out or in the wheel sits. Could be wrong though.

 

[TwistedCU]

.
Does anybody know the factory backspacing or offset for a stock 15x8 Jeep wheel????????????????????
I have a 15x7. It may (probably is) be slightly different.

anybody have a 8" "Canyon" wheel they could measue??? I need the measurement the way Gadget posted, as this is how the aftermarket wheels I've been looking at are sold.

 

[TwistedCU]

Stock TJ rims in a 15 x 8 canyon has a 5.5" backspacing, thats why they look like front wheel drive rims. Hope this helps The specs and ways to measure are straight from american racing.

Sorry ecor, I missed that That's what I was looking for. Thanks alot!