I was told by my Brother in law the butcher that Prime Rib is a standing rib roast that has been aged at least 30 days.. Don't know what is actually correct, I may have to ask google :)
Go higher on that bad boy. 325ish. I can't imagine getting a good crust at that low temp if you're stopping at 125. Or cook it low to 110, then put it on a very high temp grill and sear the outside for the last 10 degrees. Never done that for a prime rib, but it sure rocks a tri tip or thick steak.
YOU WANNA THROWDOWN?
You should! Fun and fabulous prizes await you!*
I have a bunch of stuff that cooks meat outside using some form of combustion.
*Actual prizes may not be fabulous. It all depends on what your definition of fabulous is. You're not going to win a car or anything, so don't get your hopes up. Just trying to give you realistic expectations.