Http://www.bfgoodrichtires.com/tire-sel ... re-details
This is the sort of information you need to check out. It gives load/speed ratings along with rim widths. Most tyre manufacturers give you this. I consider this information authoritive.
It is rather amazing how after a long debate on a tyre wear rate between posters it gradually emerges that one is running the HT highway tyre carcass and the other LT light truck carcass. Toyo, Goodyear, etc run different construction within the same range. BFGoodrich used to get slammed in the USA for having some of their KO ATs snow rated and others not. They standardised with the new K02 version to all be snow rated. So buyer be informed.
And on rims! Never have I been told so much boy bovine byproduct. I have seen so many illegal and ill advised fits to make me shudder. Finally, I found a brochure that recommended that their rim load rating be selected to match the tyre. Just about every rim being sold to me was under the standard tyre's load rating.
You then have the law on tyre diameter that varies between state and if ESC is fitted or not. General rule for non ESC equipped vehicle is no more than 50mm increase in diameter without certification. ESC equipped vehicles need a lawyer to figure out each State's rules with safest been no change.
Just a case of needing to research. When a friend turns up with a new AT tyre claiming extreme strength and you see it is a HT you know that they have been conned but often best to keep the peace and smile and nod.