Not sure if my 63 is the same but I have Hoosier QTP 29 x 11.5 tires in my stock wheelwell's on my 63 and it's the biggest I can fit in there. My springs are not moved and I have about 1/2" on the inside and outside of the tires. The tread is actually only about 10.5 as the 11.5 stands for the tire width. I could actually fit a 30" tall I believe as I have room to go taller but not wider. Ron