With regards to the FACTORY tires and wheels, is there a heigth difference between the 17" and the 18" tires/wheels or is it okay to switch them off without changing the speedometer readings?
The overall diameter of a 245/45R17 is about 25.68", a 235/40R18 is about 25.40", the difference of .28" is considered by most to be nominal and OK to switch between the two sizes without recalibrating the speedo each time.
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