In this paper, we present a simple and accurate analytical model for performance evaluation of WiMAX networks with multiple traffic profiles. This very promising access technology has been designed to support numerous kinds of applications having different traffic characteristics. One of the QoS parameters considered by the standard for traffic classes is the maximum sustained traffic rate (MSTR), which is an upper bound for user throughput. Taking into account MSTR implies the implementation of a throttling scheduling policy that regulates the user peak rate. Our models take into account this policy and provides closed-form expressions giving all the required performance parameters for each traffic profile at a click speed. The model is compared with extensive simulations that show its accuracy and robustness.