offset question, need help..

[muthstryker]

Hey guys, just bought a set of wheels from my friend who bought them for his bmw but never mounted them. I dont know the acutall backspace of the wheels. just the offset, the front is 40 mm and the wheel is 19x8.5, the rear is 19x9.5 45 mm, what is the best way to figure out the backspace for the wheels?? The wheels are ASA JH8 wheels.

[Project69]

Front 19x8.5, +40mm= 6.3"
Rear 19x9.5, +45mm= 7.0"

[MrQuick]

Easiest way is to drop it on its face and put a tape measure to it.

I always get dizzy trying to explain it. But the jist is. Fronts are 40mm from the center line of the rim. Rears are 45mm Positive and negative is in or out. Being BMW i'd be safe to assume they are positive, meaning they are a deep offset or in.

Fronts 8.5= 9.5 actual width center would be 4.75 so add 40mm to that is



Rears 9.5= 10.5 actual width center would be 5.25 so add 45mm to that is....crapp, you fast typers suck....well I did need 10 minutes to regain my land legs.:rolleyes: LOL yeah what he said!

[Boesch]

The way to measure backspace if you have them in front of you is to lay them face down (preferably on a cloth so you don't scratch them). Put a straight edge across the back of the rim. Measure from the straight edge down to the flat part that goes against the rotor. That's your backspace.

You can also calculate backspace if you know the offset (assuming you know if it's positive or negative offset) You can see it on this site:
http://www.usacomp.com/terms.htm
Recall that 25.4mm = 1 inch

[Project69]

Vince you didnt have typing 101? haha

[Boesch]

...man, I guess I'm an even slower typer!

[MrQuick]

Vince you didnt have typing 101? haha ROFL....wait...how do you spell? LOL :Alchy:

[MrQuick]

...man, I guess I'm an even slower typer! LOL...actually not, you beat me to my reply to your reply...wait...nevermind. Haaa haaaaa


Did you get all that Muth??

[muthstryker]

haha yes I did thanks, so assuming that the rear wheels have 7inches of backspace. and im going to need about 4.75 inchs of backspace for them to be center im going to have to run a space that is 2.25 inchs?? and same kind of thing for the front???


also vince maybe you can go look at my post in the disc brakes too :)

thanks alot guys for the help and the link.