In recent years, the need for systems monitoring the current in ation pressure in pneumatic tires has grown dramatically. One way to monitor the in ation pressure is to use the fact that the tire reacts like a spring when excited from road roughness. The resonance frequency of the tire can be estimated with standard signal processing procedures. Three different approaches for vibration analysis are studied using a simulation model similar to the tire model. The first approach uses the raw wheel speed which is highly over-sampled. In the second approach a pre-filter is used to remove the disturbances and the third approach uses down sampling to isolate the vibration frequency. Especially bias in the estimation is studied.