Any easy ways to figure out tyre sizes?

I figured people on here would be a good bet to find out methods, but i recently picked up a set of zw3’s and want to put some bigger tyres on.
Currently have stretched tyres on them and want to know if there is any ways you guys use to make sure they wont rub, plan on lowering the car a lil bit soon just using springs so wont be able to adjust ride height after I’ve got the tyres on.