I am running a set of "15 Merc rims (whole different topic so lets not go there), code 203 that currently have a set of Macho Greenway MT 205/75/R15s on. They are not only "pooh", but are also knackered and unsuitable for any use let alone road use. I obviously hanker after some BFG/ATs but can't find them in that size, which I assume is because they don't come in that size. Does anyone know of a stockist of that size (online, with mail order) or know if I can put some of the 215/75/R15s on? I tried the WIKI of course, but no matter how basic I can not get my head around numbers without a physical demonstration of the whys and hows

Thanks in advance!
Tom