From my memory I think they only come in 37s and 35s and those are on 17 inch rims. I bet they're super expensive too!!
My quick google search came up with something similiar "The new Grabber competition tires are designed in size 37x 12.50R17 for class 1, 7S, 7 unlimited, 8, Stock Full and Trophy Truck. The Protruck series will run on the smaller 35-inch version."
"The General Grabber will be available for sale in the third quarter of 2009,” Roffler said that General plans to offer it in 14 of the most popular light truck sizes, including wheel diameter sizes from 15 inches to 20 inches and tire diameters from 31 inches to 35 inches, thus hitting the most popular fitments in the marketplace.”
05' 4x4, Auto, Locked
F&R, D44 SFA & 8.8 w/disc & c-clip eliminator , Yukon Chromo's F&R, Custom Skids, Sliders, Bumpers, 35" BFGs, 5.13 gears, Riddler & Solid Diff Covers, Superchips Flashpaq, CB, Optima Red Top, Gibson Exhaust, K&N Air Filter & a lot of other little things.