wheels and tires

[veaple]

at our shop we are having a discussion about when to do an alignment. before putting on larger wheels and tires. for example we switch from stock wheels and tire, and go to 20".

[Wojtek]

As wheels are bolted solid to the wheel hub, it is the angles of the wheel hub that determine wheel alignment angles, so in theory wheel and tyre size is irrelevant.
If you were changing old for new of the same (or very similar), and the 'old' was evenly worn, and there was no bush compliance, then there should be no difference in wheel alignment angles for old and new.
However, it is common practice to do wheel alignment very last.

Also, wheel alignemnts should be done on a regular basis, not just when putting new wheels or tyres on. For street cars, we'd suggest to have a wheel alignment done just after fitting new tyres, followed up by a quick tyre wear check at 1,000-2,000km, wheel alignemnt check at 5,000km and if all is fine, every 10,000km thereafter.

Regards,
Wojtek.