backspacing and offset

[hannibal]

Someone mentioned how to find offset if you know backspacing and vise versa. But the equation they used was incorrect.I learned that a 8" wheel is actually 9 inches from outer lip to outer lip. Its 8 inches when measured between the lips. This is why its necessary to add 1 to the wheel width.

The correct equations should beoffset = backspacing - [(width + 1) / 2]

backspacing = offset + [(width + 1) / 2]

Obviously, you need to use a common unit of measurement (inches or mm)

To find backspacing on S14 SE wheels for example...40mm offset = 1.575"backspacing = 1.575 + 7.5 / 2backspacing = 5.325"

I havent verified the backspacing on the SE wheels, but I believe the equations are correct.

[SmithSR]

flip wheel overput a straight edge across wheel LIPusing a ruler, measure backspacing

this may be easier

[hannibal]

I understand how to measure backspacing. I thought this would be helpful when you dont have the wheels lying in front of you.

Here's a little chart showing the relationship between width, backspacing, and offset.