285 40's and speedo
 

If I am understanding this right, stock tire height for a z28 is about 530mm. With my new tires on the back (285 40R 17's) the tire height is 545mm. Would this make my speedo read faster or slower than actual speed? Would it be significant enough to have it calibrated? I am trying to think about this conceptually and am succeeding in giving my self a headache! :eek2: Thanks in advance!

that link helped me out too, thanks

it would make it slower, by about .75 mph @ 60mph.

Awesome link, thanks a ton!