PURPOSE:To enable the detection of an abnormality in each tire of a plurality of wheel tires separately by connecting a transmission route using commonly each signal from a plurality of the tires to a plurality of routes for transmitting the signals separately via a snap ring between a rotary shaft and a fixed part. CONSTITUTION:A vehicle, for example, a monorail vehicle has a plurality of tires 3a and 3b fitted to an axle 4 provided on a truck frame 2 and so constituted as to be capable of traveling on a track girder 1. And each pressure gauge 8a and 8b for detecting tire internal pressure is connected to the tires 3a and 3b via each pressure conduit 9a and 9b. In the aforesaid constitution, a snap ring 7 is provided concentrically with a meter bracket 5 fitted to the tip of an axle 4. And in the snap ring 7, each signal cable 22a and 22b from pressure gauges 8a and 8b is connected to each conductor 14, 16 and 17 and then each terminal 19a-19c is connected to a display 23 via each cable 21 and 22c.