Re: Wheel width question....as well as opinion wanted.
I take it they charged you the 15x8 price? If they charged you the 15x10 price, then they have to pay for shipping both ways in most states. What did the invoice say?
Otherwise they don't have to even though it is in their best interest to do so.
I mean, honestly, all you have to do is tell them you have no problem paying the price difference between the two sets of wheels but. Then you merely tell them that you'll no longer do business with them and will never recommend anyone do business with them you know. I've noticed that both them and Tire Rack have started dropping tire lines to try to decrease overhead and make more profit. As it is, anything Tyres International has that someone else has you can get it at that other place cheaper. Who knows, maybe you were getting a deal.
How much backspacing did you get? 4"?
As far as fitment goes, there's nothing really wrong with running an 8" wheel with a 12.50 section width tire. It does dome the tire a little bit. It'll make it easier to clear the wheelwells because the center of the tire won't be as far out. It'll turn a little sharper. You can air down the tires further without the worry of losing a bead.
However, you won't have the wide stance. The tires will wear better with fewer rotations on 10" wide wheels (less doming). They'll be less likely to roll over under hard cornering. They'll have their full contact patch. Without airing down they'll better conform to the terrain.
I've run both on 33x12.50r15s. The main problem I have had with the 15x10s is that when I'd go play in areas where I'd get a lot of side load I'd get tree roots, gravel, and rocks between the sidewall and the rim. We're talking about sliding down hills sideways and sliding down an incline sideways into a rut... et cetera. I've had to break down two of my tires to get crap out of there before.
If I had the choice, I've never choose an 8" wheel for anything but sand. You can run 12psi no problem on an 8" wheel and get a nice cup in the tire. You actually have a better chance of spinning the wheel in the tire than losing a bead.