I've put M/T Sportsman Pro 31X15X18.5's on my Nova with a narrowed 9" and they tuck into the wells nicely. However, I only have 3/4 inch clearance front/rear at the bottom of the opening. This is a 4-Link car and the clearance is about the same throughout the suspension travel and my side clearances around the opening are fine.
I don't see the rear moving forward or aft at all but I am concerned about tire growth. I would think if they grew it would be in the center area but I'm not familiar with the M/T's.
Am I pushing my luck running as is or am I going to have to stretch the openings?! Maybe someone can tell me they're running that close a clearance, I'll believe it, and set my mind at ease.