What is the biggest size tire and width of rims for 17 in rims, without rubbing? My car has no lowering springs or struts or anything. It's all stock.

 

regardless of wheel diameter, most can fit an 8" wide rim with 225 tires into the wheel well as long as the wheel offset is at least +50mm. now if you decide to run 235 tires, your wheel offset might need to me a couple of mm's higher to offset the added width, but i'm not sure since i don't recall reading about anyone running 8s with a 50 offset and 235 tires. if you don't ever intend on lowering, you can probably do 8s with 225s and a 45ish offset...the only concern is when the suspension compresses, but otherwise it should be okay.