This hack has been known to the dirt bike community for a while now. https://www.google.com/search?q=dirt+bike+tennis+balls&tbm=isch https://www.google.com/sea

This hack has been known to the dirt bike community for a while now. https://www.google.com/search?q=dirt+bike+tennis+balls&tbm=isch https://www.google.com/search?q=dirt+bike+tennis+balls&tbm=i... Also, there's no need to make this so complicated, you can just shove the tennis balls into a normal tire.