The 17" is slightly smaller than the 16"s by barely 8mm dia. The speedo and tacho are quite inaccurate so unless you use gps & something to read the engine rpm from the ecu it's a bit of a guess.
Easiest way is, if the ratios are to long, use smaller wheels/tyres, to short, bigger ones

Whichever way you go, it'll be wrong on some courses.