whats the widest wheel i can run in the rear?

with 18's on the rear of a mazda wahts the widest wheel i can run ( i mean the distance between the frame and the inside of the bed), the rear end is at a hotrod shop getting narrowed but I dont know how much to narrow it, to achive the biggest lip on the widest wheel. Thanks

not sure on a factory frame,just measure from the frae to the top of the inside of fender how much r they gonna charge you ?

i wish i could measure it, but the frame is sepearte from the bed, and i can't really put it back together right now. the rear end im not sure how much hes charging me, but probably $1300+, but thats for the big wilwood brake kit, new axles, labor, bodywork and paint.

ill measure mine tomm and post up

i believe its 56" though

Good luck on narrowing you factory rearend.

I took mine and was told 3" a side was the least i could do due the splines inside