need help with tire/rim sizes
 

Hey whats up. I have a 2004 dodge 3500 cummins quad cab short bed single rear wheel. I am wanting to get some kmc monster wheels in 20x10 or 20x9. I just wasnt sure on how big a difference there was between the two. I am only wanting to run a 33 inch tire and probably no bigger than 12.5 inches wide. What would you guys reccomend. Also does anybody know where you can find a good deal on these rims or on a set of pro comp x terrain tires or nitto mud grappler tires. If so let me know please. Thanks alot

John