Inner Tubes

As regards the inner tubes we have to verify first the diameter! (wheel of 20'' 26'' 29'' etc..)
Consider that if we call a wheel 29 (for example), the size (29) refers to the diameter including the tyre and the rim, so the rim will be 28 inches and will require an inner tube of 28!
Very important is also the width. In the technical data this refers to the second number.
Ex. 20'' x 2.125 (20'' is the diameter, 2.125 is the width)
For trial (for example) is important to mount an inner tube a little more "chubby", the ones for scooters are fine, even if they are more expensive and heavier.
 

For more info about the rims please go here: RIMS