Tires are one of the major sources of noise and vibrations in vehicles. The vibration characteristic of a tire depends on its resonant frequencies and mode shapes. Hence, it is desirable to study how different parameters affect the characteristics of tires. In the current paper, experimental modal tests are performed on a tire in free-free and fixed conditions. To obtain the mode shapes and the natural frequencies, the tire is excited using a mechanical shaker and the response is measured using three roving tri-axial accelerometers. The mode shapes and resonant frequencies of the tire are extracted using LMS POLYMAX modal analysis. The extracted mode shapes in the two configurations are compared using Modal Assurance Criterion (MAC) to show how mode shapes of tires change when the tire is moved from a free-free configuration to a fixed configuration. It is shown that some modes of the tire are more sensitive to boundary conditions, while other modes do not change when the boundary condition changes. Furthermore, the effects of inflation pressures on the resonant frequencies and mode shapes of the tire are studied by varying the pressure of the tire and measuring the change in modes of the tire.