Originally Posted by attworth

BS is the measurement from the back to the mounting point, not the true center.

Look at it this way.

8" wheel. 4" backspacing. Say it sits exactly even with the fender.

9" wheel. 4" backspacing. This will be 1" out from the fender.

Stock - 7.5" wheel, 5.5" backspacing. (2" from hub to outside of wheel.)
New - 9" wheel, 4.75" backspacing. (4.25" from hub to outside of wheel.) <--- this yields 2.25" more than stock, sticking out from the fender.

New wheel width (minus) Old wheel width.
Old wheel BS (minus) New wheel BS
Add those numbers

That help? Offset is a whole other ballgame.

Originally Posted by jasonkola

you do not split the 1.5 in half. the backspacing is the distance from the mounting surface back of the wheel. so you add the whole 1.5 to the outside of the rim. plus you have to add the difference between the backspacing which is .75" which adds up to 2.25" further out than stock. if you do not beliefe me you can go and ask in the after market wheels and tires forum and you will get the same answer. there is a few experts in there who know more than me on wheels who can confirm my answer.

Originally Posted by Tylus

^ is that the rims you're talking about? I think that looks pretty dang good