NEED SOME EXPLANATION ON WHEEL OFFSET AND BACKSPACING

[ARPM]

I was browsing some wheels today at *bay and checked a few bullit style wheels for the classics with the following specs, 17"x8", 0 offset,4.50 bs. As far a i can remember the formula for calculating offset is, offset=W- bs/2. So if the width is 8" and the backspacing is 4.50" the offset is positive "1.625. Am i wrong?

 

[ron67fb]

https://www.rsracing.com/tech-wheel.html

 

[DK832]

Vintage Wheel Works

 

[96 DOHC Cobra]

Vintage Wheel Works

So, a 17 X 8 wheel is actually 9 inches wide.

 

[INDSKYS]

I THINK I RAN A 4.5 REAR BS AND A 3.5 FRONT BS TO GET 16X8 WHELS AND TA KDWS TO FIT WITH NO FENDER ROLLING AND NO TIRE RUB IN REAR EVEN WITH PASSENGERS IN BACK . SHREDDING TIRES --SUX LOL 245-50 REARS 225-50 FRONT

 

[ARPM]

So, a 17 X 8 wheel is actually 9 inches wide.

that's exactly what i was talking about!

 

[stang66convt]

backspacing

i have 17x8 with 225/45/17 om a 66 mustang..offset-0
4.50 backspacing...have no problems

 

[1985GT50]

i always thought offset was wheel width minus backspace subtracted from width/2.... so (8/2) - (8-4.5) would be negative .5 inches or -12.7mm offset. what am i missing?

 

[5280/4]

i always thought offset was wheel width minus backspace subtracted from width/2.... so (8/2) - (8-4.5) would be negative .5 inches or -12.7mm offset. what am i missing?

you are right

maybe its a typo? but i also recall from somewhere with offset you measure the outside of the wheel for total width. not the inside bead like normal wheel measurements?

 

[Capt Dan]

The measurements are taken in different places. Assume a 1/2 inch lip on each side makes a rim that takes an 8" wide tire (measured from the inside face), 9"wide (measured from the outside face).