I am thinking about putting 295/75-16 tires under my 2003 duramax extended cab and mounting them on 16X9 rims. is this rim size to big for these tires or should i go narrower? and as far as tires go has anyone had good luck with procomp mud terrains? and any tire recommendations would be apreciated.

I quick reference I use for tire/wheel sizes is Tirerack. Look up your tire size and check the specs for load ratings, wheel sizes, diameter, etc. It appears the 295/75-16 is intended for a rim size of 7.5"-9.5". You should be just fine with 9"

rim size is fine for tires, but you will rub, unless you modify.

I had Procomp Mud Terrains on my truck for the winter & they were an awsome tire. I took them off so I wouldn't wear them out this summer. I was running 265/75 on stock rims.