The exterior sound emission of a vehicle is an increasingly important criterion for the homologation of road vehicles. Until recently, it has been measured outdoors, but can now be evaluated in a laboratory environment using a linear microphone array and a stationary vehicle on a rolling bench. Within this procedure, the tyre noise contribution, as well as the various noise source contributions, can be individually estimated and analysed by further using a near field microphone array in close proximity to the tyre to characterise the tyre source. This work assumes a low frequency tyre model which predicts the structural behaviour of a tyre up to 1 kHz. A microphone array in the far field is used to estimate the far field pressure spectrum of the source. The tyre is then embedded into an inverse method model, where near field pressure observations are used to estimate a simplified equivalent radial velocity distribution on the tyre. The equivalent source distribution and the far field microphone array are then utilised to synthesise the far field spectrum of the equivalent source and comparison is made between the original and synthesised pressure directivity. A number of p-norm regularisation techniques are also introduced to improve the accuracy of the equivalent source and synthesised pressure estimates by optimising the number and position of the equivalent sources. Corresponding measured results are also shown to highlight the validity of the method.
