Three tyre systems are relevant for tubeless operation. The first is tubeless or UST, in which the tyre is completely sealed by a vulcanised butyl layer. Such UST tyres are becoming increasingly rare due to their high weight, high rolling resistance and lack of self-sealing properties. Tubeless-ready tyres, on the other hand, are clearly gaining ground. Tubeless-ready tyres are not tubeless tyres. However, they can be converted into tubeless tyres with the help of sealing fluid. The tyre bead and carcass are optimised for tubeless operation, but the sealing and repair function is performed by a liquid sealant. Schwalbe, for example, has adapted its Evolution line of tyres for this purpose and labels them with the abbreviation "Tubeless easy". This means that these tyres are significantly lighter, have better puncture protection and lower rolling resistance values. Some standard tyres can also be converted to tubeless with sealant, but they are not always safe to ride on. Sealing does not work reliably and quickly on all models either.
