Do I need spacers?

[TJM]

I have a set of GoodYear Duratrac 265/75/16's on factory rims, and the clearance between the tires and the UCA is less than my finger. It doesn't look like there's any rubbing on the inside of the tires, but it's ridiculously close.

Also, I am preparing to do the Tundra caliper upgrade, and I don't know how much (if any) the Tundra rotors will change the tire/UCA distance.

Do I need to add spacers? If I don't "need" to, would it hurt if I did?

Thanks