its called belgian amber ale. it is very close to fat tire. so much so my friends ask me to brew it for any special occasion. of course they dont sell fat tire in oklahoma so seriously side by side they pick the high gravity kit to be better then the bottles.
Don't be mislead though, Fat Tire is an American ale not a Belgian which is a common misconception. The brewmaster recommends an American ale yeast in this BYO article
I had the best luck when the Fat Tire yeast was available for sale. That helped quite a bit. I have since moved on and found a lot of better beers to clone and or brew, so I don't even have any more yeast available.