Backspacing to offset conversion!

After searching every site and forum looking for pics of the backspacing i'm installing to no avail. (Just in case - 3.5 RE super flex - 31x10.5 - 15x8's BS either 4" 4.25" or 4.5") I gained a little knowledge about backspacing and offset.

Here is a rundown of what correlates to us and our needs.

This may work for other widths of rims with a .5" lip on both sides. However I am basing this off of a 15x8 inch rim.

Take the 8 inch width and add one inch: (8 + 1 = 9)
- This takes into account the lip which is around a 1/2 inch.

Divide by two to find centerline: (9/2 = 4.5)

Now that you have center line your offset measurements will come into play.

A few conversions:
0mm = 0" correlates to 4.50" bs
6mm = .236" correlates to 4.25" bs
12mm = .472" correlates to 4.00" bs
13mm = .511" correlates to 4.00" bs
19mm = .748 correlates to 3.75" bs

These offsets will of course have to be in the negative direction or towards the axle.

Subtract converted offest from centerline.

So,

Rim Width plus Lip width (I used a 1/2 for each lip)
Divide by 2 to get centerline
Find offset of rims of interest
Convert offset to inches
Subtract offset (in inches) from centerline
You get your Backspacing


I could be totally wrong but this is just what I got out of it! And it correlated with the rim websites. Believe me I've been through a lot of them.

Ah, took me a minute but I gotcha,but why all the math?

XJ 4-play said:

I could be totally wrong but this is just what I got out of it! And it correlated with the rim websites. Believe me I've been through a lot of them.

Click to expand...

Damn!Why all the math!!

Ha! Some people need pictures, some need words and some need numbers. And there ya go! Leaves very little interpretation which around here there is definitely no lack of