How far can I play with my offset? I'm not going any further than 45mm to 50mm, depending on the wheel. Am I ok?
you're fine 48 to 53 is the magic number, but also keep in mind that your wheel width plays into this a little. The wider the wheel, the lower the offset you might need to run to keep from rubbing inside.
I have a set of wheels/tires 17x7 225/45/17 i believe it's 42mm. Could i run those on my wrx? My car is not drop....
you could run those. The offset is a little off, but I've been running a +40 offset on 7.5" wide wheels for 3 years with no adverse wheel bearing issues
One thing to note... What model you are trying to fit wheels onto plays a huge role, as well. A wheel that fits one Impreza, does not fit all (even if you ignor the 5x114 bolt pattern on '05+ STis). Also, tire width/profile will be a factor if you are near the limit. Trust me, I know... Ever try to fit a 17x8 +48 with V710s on a '00 RS? Spacers and fender rolling required.