Slosh Tubz question

[rip2174]

Just installed the slosh tubz yesterday. Tried to mount them as tight as possible to the inner fender. Hooking to outside of the fender and measuring to the inside of the tube, I'm getting 2.5 to 2.75 in. Does this sound right. Wont be able to reduce that without cutting material off the tubz. Also after I mounted the fenders on truck, with the cab about 2-3 in off ground, the tire rubs the tubz. Have stock wheels on the truck right now and full Porterbuilt front suspension. Will I need to get different wheels?