As a rule of thumb, you need to use an inner tube if your tyre is marked as ‘tube type’ or if your wheel is a tube type. However; there are exceptions to the rule. Bridgestone uses a UM letter code to define tyres with a marking ‘Tubeless, use tube on a tube type rim’. This means the tyre is developed as a tubeless tyre within rim standards for a tubeless rim. But this tyre can still be used on a tube type rim, using an inner tube. These tyres have been tested and validated regarding inner liner friction and bead setting.