Just because a wheel fits without rubbing 
doesn't mean it'll look right. The wheel 
dimension that effects it's appearance 
on the car is what I call "front spacing". 
It measures from the hub to the outer 
bead and determines the placement of 
the wheel relative to the wheel well. 
Once you exceed a certain frontspacing, 
the tire sticks out past the fender. 
You calculate it by subtracting the offset 
from half of the wheel width. For a zero 
offset wheel, the front spacing distance 
is simply half of the wheel width, got it? 
So check the chart below for what wheels 
your car has on it. Then compare it's 
frontspacing with any other wheel to 
see if you need adapters to make up 
the difference.

(Also, backspacing measures the 
distance from the hub to the inner 
bead, plus a little extra for the wheel 
lip. If you exceed a certain 
backspacing, the tires will rub 
in the fenders. I haven't calculated 
backspacing yet.)

(WIDTH / 2) - (OFFSET / 25.4) = FRONT SPACING

OEM CORVETTE WHEEL FRONT SPACING:

84-87 base
8.5"/2 - 32mm/25.4 = 2.99"

84R-87 Z51
9.5"/2 - 38mm/25.4 = 3.25"

88-96 base
8.5"/2 - 56mm/25.4 = 2.05"
9.5"/2 - 56mm/25.4 = 2.55" 
(also used for fronts on some models)

ZR1 rear
11"/2 - 36mm/25.4 = 4.08"

Grand Sport rear
11"/2 - 50mm/25.4 = 3.53"

C5 base
8.5"/2 - 56mm/25.4 = 2.05"
9.5"/2 - 65mm/25.4 = 2.19"

C5 Z06
9.5"/2 - 54mm/25.4 = 2.62"
10.5"/2 - 58mm/25.4 = 2.97"

C6 base
8.5"/2 - 56mm/25.4 = 2.05"
10"/2 - 79mm/25.4 = 1.89" 

C6 Z06
9.5"/2 - 40mm/25.4 = 3.18"
12"/2 - 59mm/25.4 = 3.68"Power Steering Trivia