Any fairly-smooth cruiser bike tires will work, and fatter ones can absorb much shock (if you don't over-inflate them!). I have some generic 2.125's on mine, which is about as wide of tires as you will find for typical rims. The Worksman bike I started with came with Cheng Shin tires which were entirely adequate, but I wanted white tires, so I bought some $15 white Kendas.
You can get Kevlar if you want to pay for better puncture resistance, but there's a few ways to handle the issue of flat-tire-prevention as well.
If you want the fattest "street-tread" tires around in 26", then (I think) they would be the Schwalbe Big Apples, which are available in both 2 and 2.3 inches wide (in 26"/559 size). They cost $45 each however, and the 2.3"-wides may give chain-rub issues in certain low gears. I have them on a non-motor recumbent, and I'll warn you that most typical 26" wheel bicycle fenders just barely fit over a 2.3" Big Apple tire.
...If you happen to have a Golden Eagle (belt-drive) kit, I would also warn that the 2.3" Big Apple is so fat that I don't know that you could even properly line up the drive ring and the engine's pulley correctly. This would depend exactly on what kind of rear hub your bike had; mine has a 3-speed Shimano Nexus.... I don't own a Chinese chain-drive kit, so I can't say if they'd have the problem or not.
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Ultimate setup:
If you're blowing out your wallet on this project, then you want to get wider rims as well. Most MTB's come with rims that are WAY too narrow, what you want is downhill rims on it, you want rims that are 1.25 to 1.5 inches wide (outside measure). And that advice is valid for MTB's that are motorized or not.
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dose anyone use special tires? any tips would work. thx
