The 11" wide tires should fit. The general rule of thumb is 4". You can mount a tire 4" wider then your rims. In your case you have 7" wide rims, so mounting a 11" wide tire, even a 11.5" tire is fine. If you wanted a 12" tire, then go for at least a 8-9" wide rim.

Will you rub? Maybe at full crank. Just don't turn as sharp, or like suggested, crank your torsion bars some.

Personally, I wouldn't buy Thornturds. I have heard way too many negative comments about them. If your seeking a All-Terrain tire, I highly recommend BFG All-Terrain tires. It's hard to beat them on or off-raod. They have the most victories off-road compared to any tire made. They have won the last 19 consecuative Baja 1000 races. Check out their web site for more info.