A tyre pressure monitor for the paired wheels at one end of a vehicle axle in the form of a hub which bolts to the wheel using the wheel nuts. The hub contains a tyre pressure gauge for the inner wheel and a gauge for the outer wheel. Air tubes connect each tyre to the gauge and an exterior air input coupling for each tyre projects from the hub in order to be accessible to the depot air hose. The driver reads the gauge and adjusts the tyre pressure using the air input coupling when necessary. Versions with a single gauge with a separate scale for each tyre of the pair and with one gauge for a single front wheel are described.