Here you will find all the tubes relevant for trials sports.

For 19" rims, always use a 20" tube!

Light tubes (thin-walled tubes) work well for the front wheel, and sometimes for the rear wheel for children.

With a light tube, you can save a significant amount of weight for relatively little money!
If weight is not a concern for you and you prioritize reliability, it is best to choose a standard tube.

Active filters