Improvement in a tyre inflation system in tyre-changing machines

Improvement in a tyre inflating system installed in a tyre-changing machine (1) and in communication with a pressurised fluid source and a pressurised fluid delivery member (3), comprising at least one pressure limiting valve (4) arranged upstream of said pressurised fluid delivery member (3) in said inflating system, the said pressure limiting valve (4) being arranged to limit the delivery pressure at at least two different maximum pressure threshold levels which can be alternatively selected by a user.