True true Vince.
To add on that, and this Alberta only, you can increase your axle weights via the use of 14ply tires. This on trailers only, and in alberta only.
My 14 ply tires on my two 7000lb axle equiped gooseneck up the rating from a total of 14k, to 14.8k.
As for trucks, you can never increase the axle rating with tires, but you can decrease it. For instance, if you put a C or some D rated tires on a 1 ton truck, they would likely be rated for less weight then the actual axle. In that instance, they would reduce you rating to that of the tires.
Fortunately, pretty much any and all E rated tires are rated for more then any domestic axle on the market. So when dealing with 3/4 and 1 ton trucks, you are always safe with an E tire.
Great thread for those starting out with any type of towing actually.