Check the diameters of the tires. + sizing doesn’t necessarily mean taller tires.
335/35/17 is 26″ and OE 335/30/18 is 25.9″ i.e. not enough to worry about.
Most will use an inline recalibation box if gears are change. hope this helps.
Viper-New-Rims.jpgI have original 17s that I only use at track now and have 2004 Rims (18/19 stagger) on car and its only about 3-4 miles and hour different at 65 (from watching GPS vs doing math). It looks like 61 mph on dash is about 64-65 on GPS when running the 18/19’s. After getting adjusted to it gave up on looking for a calibration unit given how small.
I plan on changing my stock 17″ for a set of 18″ rims. Aside from knowing the speed differentiation and adjusting for it, can the speedometer be re-calibrated to compensate for the size difference, and is it worth it?
