My car came with 205 60 r16 and I have a set of new 17" rims, just wanted to know what is a general size of tyre to put on that it doesnt throw my speedo in my 3rd gen.

Cheers

Pretty sure 235/45 are common for 17's.. won't mess your speedo up to any point that you'd notice.

This is assuming they are 8" wide?

Have a play here (http://www.rimsntires.com/rt_specs.jsp).

17" rims on Magnas came standard with 225/50s. Like Alan said, 235/45s are a common choice, but ideally you'd have a wider rim - manufacturers recommend that the minimum width is 7.5" (if you bought a set of Mitsu rims, they'll only be 7").

Have a play around with the tyre calculator GRDPuck linked to. Your tyre diameter can legally vary by -/+ 15mm in NSW afaik.