Gearing Question - 1/8 Buggy

Hey guys,

My buggy conversion is finally almost finished and am now thinking about gearing since I know what all of the components I will be running. Here is what it is looking like:

XTM X-Terminator 1/8 scale buggy
Castle MMM Combo with the 2200kv Motor
Zippy 5 cell 5000mAh

I currently have a 13t pinion that I was going to use but not sure what a reasonable spur gear size would be. Just dont want to run something that is going to fry the nice new motor or esc. I would apprecaite the input! Thanks.