Front Tire Size Q

Did a search and couldn't really find what I needed. Front tires need to be replaced soon, and I want to know how big I can go up front before I have fender contact issues, and shock contact issues. I'm currently running a 275/35/20 with no issues, but I don't like how stretched the tire is, and how much it exposes the lip.

Specs:
Lowered on sportlines
Velgen VMB9, 20x10.5 +45 offset
8mm spacer

Currently on OEM PP shocks, but will be upgrading in the near future. Not sure if aftermarket shocks have different clearance requirements. I PM'd velgen and of course got zero help from them as usual.

Thanks guys!

305/30/20 all around

I have 305/30/20 on the rear right now. Maybe if I'm not too lazy I'll throw those up front for a quick drive and see what happens.