I actually found replacement rims at a garage sale that were heavier than mine, ever since I have had no trouble and I ride a pretty rough dirt rode every day. As far as noise level goes, it is actually pretty quiet. I have the 2 stroke 32cc tanaka. While on the bike you really do not notice the noice at all since the motor is behind you. But honestly it is just like a small weed eater. I have asked all my neighbors if it bothers them, and they all say that can not even hear it. I have been by a handful of police officers in Thornton and not one of them has said a word. As far as vibration, there is none. The other chinese motor I had would vibrate the whole bike. Believe me you will not be disappointed once you get yours. I ride every bit of 36 miles a day round trip, and have never had a hic-up one with this set up. I actually bought it for my wife, but I liked it so much I kept it to go to work on. We do haul a trailer and two kids (7&3) behind it, and can still maintain 24mph with some light pedaling. I hope this helps.