Ok, here's a "buggy newbie" question, can I fit monster truck tires and wheels (like e-maxx) on my ofna ultra buggy? if so what kind, what size hub is ultra? 17 or is it 19mm?

Yes, you can fit them (17mm hub btw). The problem is gearing. The ofna trucks use much larger spur gears to compensate for the larger tire diameter. If you are looking to convert, see if the monster pirate center differential (and diff mount) will bolt directly onto your 1/8 scale chassis.

When all is said and done, it may be cheaper for you to find a used monster pirate.

Great, thanks for your help well, i do have another question: I have the Novarossi Top .21 engine, will that be enough power to pull big tires and wheels? I haven't run my ofna yet.

Thanks again!

If you are going to use dominator wheels and tires on your buggy, there are a couple of reasons to try and fit the monster pirate (or dominator) center diff on your chassis. The first is slow acceleration and poor throttle response. The second is wearing out clutch pads quickly (and heating the clutch bell too).