10's should work, considering that if a rim states that it is 8 inches wide this is from the inside of the bead to the inside, so in effect the ACTUAL rim width is 9 inches. Since rubber is well...rubber it stretches to fit on the rim and you should be fine with 10. I would have gone and said that you might work with 11s but thats pretty wide in itself, and streets doesnt think she will fit. Best bet, ask the tire shop what you can do with it. As for tall, I am aware of up to 70 percent height. There might be taller such as special made mud tires or something but I just don't know. SO if 70 percent is a good baseline you are lookin at a tire that is 7 inches tall at the sidewall with a 10 inch wide tire, or 14 inches of rubber, with your rim it would be a 29 inch tall tire. If its a mud tire you want, the Mud terrains are meaty lookin but dont like ice, and since I dont know where germantown is I'll just note that. They do work great for...well mud and stuff but the All terrains look fairly aggressive as well but for sheer meaty look the m/ts are what you want. I think Bf Goodrich states their tire sizes in inches and possibly a 10.5 inch wide tire might fit. Since the rim is smaller I dont see why this wouldnt work as opposed to a bigger rim and a smaller tire. This would make the tire stretch out to the bead and not the other way around. A good tire man should know. UHH, hope I helped.