Widest Duster tire?

i have a 255/70/15 firestone firehawk on mine, ita about .5 inches away from the outer side of the wheel well and about .5 inches away from the springs. its on keystone klassic 15x7 3.75 inch backspacing. when i was looking around i think its the biggest size you can go and be safe, considering sidewell flex and all. the tires have a buldge width of 10.2 inches, and like 9 inches on the road? they are 29 1/10 tall, so a little bit of the front and back of the wheel well openings on the quarters had to be cut, but it didnt matter on mine, since its all putty