I want to know if my old tires are going to fit on my new rims for my truck. I need

[tanner_goracke]

some help!? I have an 88 chevy silverado, regular cab long box. It has stock steel rims with LT245/75R16 size tires on it. My cousin gave me some newer aluminum rims that came off of his newer silverado, to spice up the look of mine a bit. They have P265/70R16 size tires on them. I have already put these new rims and tires on my truck. But the tires are getting pretty bald, and I want to put my old ones with better tread on the newer rims. Now both sets of rims are 16" rims, but the tires are different sizes as you have noticed. I just don't know if they'll fit because they're different sizes. I don't know if the rims will vary in width at all. Any help on this I can get will be MUCH appreciated!! Thank you!!