O.k., you purchasing new wheels, know the specs but not sure exactly how much it will stick out or not.

offset - good explanation found here http://www.tirerack.com/wheels/tech/offset.htm
"The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel"

so.. lets use 2 wheels

1) stock enkei: 15x6 inch + 50 offset | 6inch = 152.4mm

152.4mm/2 - 50mm = 26.2mm = distance from hub mounting surface to outer end of the wheel
152.4mm - 26.2mm = 126.2mm = distance from hub mounting surface to inner end of the wheel


2) rota slipstreams: 15x6.5 inch + 40 offset | 6.5inch = 165.1mm

165.1mm/2 - 40mm = 42.55mm = distance from hub mounting surface to outer end of the wheel
165.1mm - 42.55mm = 122.55mm = distance from hub mounting surface to inner end of the wheel

next,

122.55mm - 126.2mm = - 3.65mm = in this case, stock will extend by 3.65mm on the inside.
42.55mm - 26.2mm = 16.35mm = this is by how much rotas will extend out

 

 

Who says the ITR forum is going down? Great post

 

ttt for daytime

 

I found this calculator that does the work for you: http://toy4two.home.mindspring.com/offset.html

 

mine gives more details, but good link , if i found that, wouldn't had to do all that writing..

 

I was just going to write something similar.

Good write up

-Tommy who is still looking forward to owning a set of 15x7's