Need tire size recommendations...

[BlackenedRR]

I'm getting ready to buy new tires for my GMC, wheel sizes are 20x8.5 front and 20x10 rear. I'm thinking either a 275/35 or 275/40 on the front, and going back and forth between a 295/40 and 315/35 rear. Fitting any of these sizes without rubbing shouldn't be an issue, my only concern is I don't want the tires to look too small or too big for the wheels. I'd like to get a size where the sidewalls will end up damn near square to the wheel, or maybe a slight outer bulge. I'm looking at the Toyo Proxes ST II, so if anyone knows about pros/cons of this tire, please let me know. Thanks!