sixteen hundred gazzilion posts on this subject, U really should read alot of them to get up to speed, I am sayin this because it is alot of info u will need and more info than u will get in one thread, I only mean this to learn... Now as for the exact answer to your question, If u clean up your rims, u may find stamped on them MAX TIRE SIZE 1200 ... in a court of law u are safe up to that size, the 1250s sure do work and will for ever, but that is the propper answer, and the very popular 1100 michelins allow U to keep deuls on your truck, but that is your prefference, I will offer a liitle more also, A single tire set up in most cases will get U further in off road conditions, most that is because there is a wide veriety of widths U can use, wider tires do better in sand and rocks and narrow tires do better in mud and snow, for a basic rule this is true, there is always someone who will say there wide tire is better every where, but thats just not true, the driver is as important as the tire anyday also.. , ..and deuls are better in stability in a loaded truck every time this is also a fact....good luck,