17" -> 18" OEM wheel upgrade, do I have to change anything?

sapien · #1 (**permalink**) 01-30-08, 09:19 PM

so I scored a mint set of the OEM 18" wheels/tires which I think are an inch or so taller than my current 17"s ... besides the function in the Nav, does anything need to be done to recalibrate the speedometer or anything else?

pjbizjak · #2 (**permalink**) 01-30-08, 10:40 PM

Are you figuring the 1" because of the difference between 17" and 18"? I believe the factory 18" tires have a lower aspect ratio tire which would make the diameter difference probably only a 1/4" to 1/2" taller and you shouldn't need any recalculating.

sapien · #3 (**permalink**) 01-31-08, 01:59 AM

I'll have to double check but going by the Cadillac spec sheet, the aspect ratios are the same so yes the wheel/tire combo is a full inch taller.

Greg00coupe · #4 (**permalink**) 02-03-08, 09:41 PM

Any good tire shop can help you. I upgraded the wheels on my Corvette and according to the Garmin GPS the spedo is only off 1 mph at 70.