Tire size, rim size, how big is your limit?

Any one slapping on oversized tires on daily drivers? After completing my rear suspension with lift, I'm going to look into getting some bigger tires in the back to increase traction. Right now I'm running 225/75 on 15x7 inch SS rims on the rear. What's the widest, most beefy (thick) street legal tire I can put on a 15x7 rim? I may also scrap the SS rims for a matching set of chrome rims, smaller (maintain 15x7 inch or go thinner) in the front, larger (up to 15x10 inch, maybe?) in the rear. My goal is to get as wide in the rear as I can go, but maintain as much thickness as possible, to maintain that beefy, tough old car look.

Let me know what tire/rim match up that you guys think looks and performs the best. Thanks.