Replacement wheels for early C4

[Steven Smith]

How difficult is it to fit C5 wheels to an early C4 (86) ?
Seen a set for sale locally at a good price and because 255/50-16 tyres are getting so hard to purchase now I was thinking of changing the wheels over to 17".

 

[teamzr1]

Keep in mind, if you change the wheel/tire sizes it may then cause your speedometer to not show MPH correctly
or effecting auto tranny shift points
This would require either the outer and/or inner gears of tranny that goes to the cable to the speedo to be changed

Before making the change is use like this website to calculate the old to new wheel/tire size difference

tire/wheel calculator

Tire width to wheel width


Here is what the C5 wheels/tire sizes are

 

[Steven Smith]

My mistake there 18" rims so if I use 255/40-18 there is 1/10" difference in circumference.
I was just wondering if spacers were needed

 

[teamzr1]

The C5 chart I posted above gives the offset and backspacing, so look at the ones that are 18 inches and
then see GM specs or measure your existing rims to see if spacers are needed on hub side will bring wheels out a bit that is needed