That tire size works fine on stock rims - MTRs work fine in a rock garden but a little less so in other environments. They become a little noisy on pavement after 30 to 50 percent of tread wear, which is a real pisser considering their cost. IMHO the BFG MT is a better all around tire between the two and doesn't get louder with "age" but the sidewalls will superficially cut and scuff making them appear as if they went through the Civil War without a gun - but then again, when someone sees a ragged ass looking sidewall he will probably conclude the LC isn't a "tar baby" and all's well?
Do not listen to Junk. He isn't afraid to loudly state his mis-informed opinions. Ask him when he last went out of his driveway in a Land Cruiser.
It must be the unbelievablely harsh East Coast conditions. Out here, most people really like MTRs. They are a bit of a compromise over a Swamper, true, but who wants to DD on Swampers? That's just silly. Otherwise MTRs work great in the rocks/dirt mixed conditions of the West. One thing we don't have here is much mud, and that is where the swampers would really shine over an MTR. I personally do not like the set of BFG MTs on my FJ60, but that's just me. Lots of people really like them. MTRs are excellent all-around tires in my opinion-I'm running 2 sets of them right now.
To answer the original question, they fit great of 8 inch rims. I don't know where your tire shop is coming from.
Not only do they think your rim is 7", you gotta watch them when balancing or they'll set it up wrong and your balance will be off. They also have the wrong torque settings on their chart...something like 126, which is for steel wheels. Stand over them with your owner's manual and show them or they'll pop a wheel stud. Ask me how I know.
For years I have purchased my tires from Tire Rack, and always taken them on loose rims to be mounted. No need or opportunity to fuss over tire shop lug nut torquing practices.