Looking for new wheels for my Z3. I want to know what limitations I have.
Cheers
You need a Percy's gauge,
https://www.amazon.com/Percy-01201-WheelRite-Wheel-Simulator/dp/B002L1GFQE
cheaper on ebay i believe, especially with global carriage.
Plenty of people have made their own using a wheel spacer as the mount, probably google would help you there for plans/dimensions.
Max width will obviously mean going to coilovers to maximise space. Remember that the tyre still has to clear on full lock, you can hit the liner or the inner wing. Why something like the above is used, you can check not just for suspension/arch clearance, but liner and inner wing clearance on lock-lock
If deciding on a tyre which 'might' be close to min clearance, you MUST go to the manufacturers website for accurate dimensions, e.g. not all 225 tyres are 225mm wide, depending on the shape of the sidewall some can be 235-240. I know from speaking to my tyre fitter guy he's had folk come in for new tyres of a different make, and found the wheel won't fit back on. The tyres are the same 'size' but completely different dimensions.