I have Dodge aluminum wheels. I'm not sure of the width.
I have Cooper Discoverer 285/75s on and they have lasted 40,000 miles, a good bit more than I've gotten with General Ameri-Tracs or the Wal-Mart Liberators.
One main reason for the narrower tire is that in Mexico there are speed bumps everywhere. Sometimes there are narrow slots on the ends or in the middle where you can sneak thru without bumping if your aim is good and your tires aren't too wide. Also, on the muddy roads in Peru when I was there, we used narrow, tall tires that would supposedly sink down thru the surface mud and onto drier dirt below.
SRadke, are the M-55's good off-road? I looked on the Toyo website, and the picture above is actually for their more agressive Open Country model. I do like the E rating of the M-55, because I do a lot of heavy trailer towing.
Thanks, everyone, for all the help so far. I'll keep monitoring this.