i have a 29.5x10.5S on a 12'' rim and in the front i had a .75 clearance in the front and 2 inches in the back. on the burnout and at the end of the track it was EVER SO SLIGHTLY rubbing. so i'm assuming i was even getting those tires to grow 1.5 inches.
i clearanced the front of the fender another 1/4'' and no more rubbing. so i think you got it covered with 1'' on both sides.