Surly Fat Bike Ultra Light Tube The Surly Fat Bike Ultra-Light Tube. Yep, we just used "Fat" and "Ultra-Light" in the same sentence. It is designed to fit the biggest and baddest fat bike tires on the market. The . 8mm thick butyl rubber gets the air holding job done so that you can focus on pointing you fat bike at something gnarly. Coincidently, these tubes are also large enough to send a baby goat down river. Surly Fat Bike Ultra Light Tube Features: Size: 26 x 3. 0 - 4. 8 Valve: Presta Short 32-40mm Valve Core: Removable Weight: 310 g Floats your Goat | Surly | Plus Fat Bike Tube - 26"+ 26 X 3. 0-4. 8", Presta Valve | Rubber