Wheels question: Offset and backspacing - relation?

[MichaelD]

I know what backspacing is, and I'm under the impression that offset is how far "offset" from the centerline of the rim the mounting face is.

How are the two inter-related? How come some wheel manufacturers list offset, but not backspacing, and others, vice-versa? WUWT?

 

[NutBucket]

I've never seen backspace listed, only offset. Uhm, I dunno.....

 

[LAUST]

I'd stay with stock offset unless you get a lift on a truck, you will just trash your bearings and have uneven wear on the tread

 

[ObiDon]

I believe one is the difference between the mounting surface and the "equator" 😉 of the rim and the other measurement is the difference between the mounting surface and the inboard surface of the rim.

I can never remember which is which though. Off the top of my head, I can only think of one auto manufacturer that measures in backspacing. 😕

Edit -- Wait...maybe I'm thinking offset? 😕😀

 

[jemcam]

Never heard of backspacing either. It's not an automotive term that I'm aware of.

You're wheel offset is important because with different wheel offsets, it will affect the camber and SAI, or Steering axis inclination. It's also why you see so many ricers that have the inside edges of their tires worn out, because the alignment adjustments have to be changed with different offsets. The weight is supposed to be evenly distributed across the tire, and if you put on wider wheels with lots of offset, the majority of the weight is resting on the inside of the tire. If you draw an imaginary line from the top of the strut to the middle of the stock tire and rim, that's where you'll see what I'm talking about. Take a wider wheel with lots of offset, and you'll see that if you haven't changed the alignment, the weight is on the inside of the tire.

Toe in, and caster are not affected by wheel offset.

 

[MichaelD]

Originally posted by: LAUST
I'd stay with stock offset unless you get a lift on a truck, you will just trash your bearings and have uneven wear on the tread

The truck is lifted about 1.75 inches, front and rear. The "problem" is that I'm trying to stuff 285/75-16 BFG ATs on there and I'm worried about rub.

I could put the tires on my stock rims, as I know of one individual that did that exact thing and has no rubbing, even at full stuff. (he has the same make/model/year as my truck)

My issue is that my stock rims are the "upscale and slightly nicer" ones and I don't want to risk bashing them up. I wanted to get some inexpensive aftermarket rims and if they get banged and bent *shrug* I just replace 'em. It's tough.

My truck's stock rims have a 1.25 inch positive offset. Stock rims are 16 x 7 inches but I'm looking to go to a 16 x 8 rim as it's a better fit for the 285.

 

[LAUST]

Backspacing is the measurement from the Offset of the wheel to the back of the wheel (Brake side)

Here is a better explanation then I can give