I personally have run two different sizes on both front and back, now I have 245 40 18 front, 275 35 18 back, I had 275 35 18 front and 315 30 18 rear, front was too wide stuck out a good 1/2 inch past fender, I liked the rear but rubbed on the outside lip; I had to bend the lip up. I like the way my setup looks right now, But I will be changing the rear to 305 35 18 next time. The 245 in the front fit perfectly just inside the fender.