$40 ??? great deal I would keep same tires. If they handled the loads on the truck before, they should hold just fine. My trailer is the same but 3/4 ton I have stock wheels/tires from 05 Duramax Load range "E". Dont know the difference in capacity between load ranges. I will tell you from experience, keep a jack stand under the bumper if you dont want any freaked out kids or drunk adults
when they step on the bumper Its funny til someone starts bleeding