I have a 2003 dodge ram 1500 with hemi, and 20inch crome stock rims. I have these extra tires and i was wondering if the would fit on my truck and i would buy some rims if they will fit. They are 315/75/R16 which are 34.6inch/12.4inch/R16. And i would buy 16x8 rims. Would the 16 inch rims fit on my truck? would they clear the brakes and other stuff?

Unless your truck came with the 16 inch wheel package, no they will not clear the brake calipers. a 17 will fit thought.
Dan