I don't know what your stock rims are, but most likely, if they are not cast aluminum and are in good shape, they will do just fine with 265s, with a load up to the tire rating. Look
HERE for a similar discussion thread on tire size and rim width. BTW 18 inch tires are WAY more expensive than 16 inch tires, so you should take that into consideration in choosing new rims. Once again, if you are going to be heavy and want the most piece of mind, go for the 19.5s. Having said that, if 265s will give you the weight capacity you need, then look for 16 inch rims and perhaps your stock rims will be OK, and if they are the forged aluminum 6.5" wide PYO rims, then they will be OK. Also the 16 inch 3500HD steel take off wheels should be OK. I am giving only my opinion, supported by my experience on running 6.5" rims. In the end you should do what gives you the most piece of mind, after making an informed decision...Terry
