I have never looked that closely at a Grom, but I know the chain on an NSR50 comes pretty close to rubbing the outside of the rear tire. If you ran the Grom wheels-- it seems like the chain would be the problem there. Not even sure if the axles are the same width or not. Let me know what you guys come up with. I'll likely just run the wheels that come on my NSF100. The gain may not be worth the trouble. --L*64