In the existing coupling vibration analysis of vehicle bridge，the influence of vehicle dynamic characteristics and flexible tire on the vehicle bridge coupling vibration response can not be accurately considered. In order to further study the influence of pneumatic tire pressure on vehicle bridge coupling vibration，the linear elastic rubber material is used to simulate the tire and define the air pressure in the tire based on LS-DYNA program. Combined with the structural parameters of the commonly used heavy-duty three-axle vehicle，the dynamic characteristics of the vehicle suspension system are simulated by using the spring damping element，beam and shell element，and a three-dimensional vehicle model is established. Based on the test results of the real bridge and the response surface method，a high-precision finite element bridge model is obtained. The vehicle subsystem and the bridge subsystem are coupled together to form the explicit vehicle bridge coupling vibration analysis model through the contact algorithm built in the explicit solution program LS-DYNA. The correctness of the method is verified by comparing the calculation results with the measured results，and the influence of tire pressure on bridge vibration is analyzed.