Hey I have a set of 18•9.5 fittipaldi force rims...does anyone kno the offset on these? If not, can someone tell me how take a ruler and figure it out? Thanks ahead of time

 

1) Measure from front lip to back lip...this should measure 10.5 inches if the wheel is really 9.5" (an advertised wheel width does not take in to acount the wheel lip, roughly 1/2" front and 1/2: back.
2) Lay the wheel face down and lay a straight edge across the wheel.
3) Measure up (from the face of where the wheel mounts to the hub) to your straight edge. Convert this number to millimeters (inches X 25.4 = mm).
4) Subtract 12.7 mm to account for 1/2 inch of lip (as mentioned in step 1)
5) Subtract 120.65mm. (I got the 120.65 by converting the center point of your 9.5" wheel (4.75") to mm...if your wheel is not really 9.5" when measured as described in step 1, this will need to be altered).
6) This number is your offset. It will likely be positive rather than negative if the wheel was on an F-body.

 

Ok so wen I flipped the wheel over it was punched as a 18x8.5...either way I had 6"from where the hub met the mount converted it to get 139.7
Subtracted 107.95(8.5x25.4)
And got 31.75

now my question is wen I get tires do I base the size off of a 8.5 or 9.5" rim

 

32mm is a pretty common offset - get tires based on the 8.5 width (245-275 should work fine)

 

Agreed...I think a 245-255 would look best. I run a 245 BFG KDW2 on an 8.5" wheel on the front of my '76 T/A and I think it looks perfect...my 2 cents