correct wheel offset

[dazandjude]

I've just bought a '91 mk2 1.8 16v with 16s. The tyre size on the wheels is 205/45 but these scrub the back arches a bit, is this because the tyres are too big, I've been told they should be 195/45, or is it because the wheels have the wrong offset?

I'm also thinking about putting some 17s on her and would like to know what the correct offset should be.

[Simpson]

probably too wide, possible offset too, on 15s they have 195 50 15 usually or 185 55 15s, 17s would calculate 205 or 45 17 i think, oir possible 215 on the back, i believ there is a website that works it out cant remember which, someone on here will know. 

[Chris-White]

A safe offset on a mk2 is between 35 and 25, if that helps.