Rim VS Tire Size

[Scufty]

What re your thoughts on this guys...
I currently have 15x10 centerlines with a 4 and 7/8 backspace with 28x10x15 tires MT Sportsman radials

could I go with a 15x8.5 with a 3 and 5/16 backspace with the same tires?

Thoughts?
Anyone running a 28x10 on this rim size?

[Scufty]

nobody else runs 28x10x15 tires?

[MaSnaka]

Scufty, I have 15x8.5 with the MT ET street drag radials 275/60/15 I think the width of your rear end is going to make the back spacing critical. What do you want to kmow that I can help you with? Too bad you not close enough you could try them on for size.
John

[DanEC]

I think a 10 inch thread width tire will work OK on an 8-1/2 rim. The rim width might be a little marginal but not by much.

[strictlypersonl]

You realize that going from 10" x 4-7/8"B.S. to 8.5 x 3-5/16" will move the tread edge out by almost 3/4"?

[Gaz64]

The 8.5 inch rim only comes out an additional 1/16 inch.

[392cobra]

Originally Posted by strictlypersonl

You realize that going from 10" x 4-7/8"B.S. to 8.5 x 3-5/16" will move the tread edge out by almost 3/4"?

Yep,the rim is 13/16" further outboard with the 8.5 X 3-5/16" B.S.

[strictlypersonl]

Originally Posted by Gaz64

The 8.5 inch rim only comes out an additional 1/16 inch.

I wasn't talking about the rim, I was talking about the tire's tread corner, which is approximately the same no matter what the rim width. The centerline of the tread stays with the centerline of the wheel, so the place most likely to rub (the corner of the tread) moves out about 3/4". The widest point of the tire (at the bulge) moves out about half that amount.

[xb-60]

You're spot-on Bob. The outer edge of the rim for both setups is in exactly the same place; the inner rim on the 8.5" wheel is 1.53" further out; that makes the centre of the 8.5" wheel (and hence the centre of the tyre) 0.78" further out, so the outer edge of the (same size) tyre moves out that much as well.
Cheers,
Glen

[FWB]

not relevant to the backspace, but aren't the 15x10 sportsmans 26" not 28?

[Gaz64]

Originally Posted by strictlypersonl

I wasn't talking about the rim, I was talking about the tire's tread corner, which is approximately the same no matter what the rim width. The centerline of the tread stays with the centerline of the wheel, so the place most likely to rub (the corner of the tread) moves out about 3/4". The widest point of the tire (at the bulge) moves out about half that amount.

Originally Posted by xb-60

You're spot-on Bob. The outer edge of the rim for both setups is in exactly the same place; the inner rim on the 8.5" wheel is 1.53" further out; that makes the centre of the 8.5" wheel (and hence the centre of the tyre) 0.78" further out, so the outer edge of the (same size) tyre moves out that much as well.
Cheers,
Glen

Yes boys, you are both near enough correct, sorry for confusion.

[Scufty]

stricklypersonal I think you are mistaken?

the tires I have are 28x10x15 I put them on the 15x8.5 rims with the 3 and 5/16 backspace...the tire does not come out hardly at all on the outside...just comes IN on the backspace. They seem to be working fine. FYI they are also on the front of the car and the previous rim and tires were 15x10 with a 4 and 7/8 backspace. I saw no reason that there would be an issue going to a smaller backspace? So far so good. pretty tight though ( the old set up was very tight as well mind you.
When I put the new rims up againt the old ones the measurement from the lug holes to the front edge of the rim was the same on bot the sets....the backspace is where the inch and a half was made up 10 vs 8.5

[Scufty]

after rereading I guess it all sounds about right ..I will look closer when I get back home again ...seemed ok when I took it for a rip last night ...