The properties of contact patch are key factors for tire modeling. Researchers have paid more attention to the contact patch shape and vertical pressure distribution. Some innovative concepts, such as Local Carcass Camber, have been presented to explain special tire modeling phenomena. For a pragmatic tire model, a concise model structure and fewer parameters are considered as the primary tasks for the modeling. Many empirical tire models, such as the well-known Magic Formula model, would become more complex to achieve satisfactory modeling accuracy, due to increasing number of input variables, so the semi-empirical or semi-physical modeling method becomes more attractive.
In this paper, the concept of Tire Carcass Camber is introduced first. Different from Local Carcass Camber, Tire Carcass Camber is an imaginary camber angle caused only by lateral force on the unloaded tire. Similar to tire camber, Tire Carcass Camber is assumed to have the same effect on the properties of contact patch and also on tire mechanics. Thus in tire modeling, the camber effect can be expressed as the function of the total camber, which is the sum of tire camber and Tire Carcass Camber. In order to demonstrate the rationality of Tire Carcass Camber concept, the improved semi-physical model of tire overturning moment is presented, and the modeling accuracy is compared with the original model. The comparison shows that the concept of Tire Carcass Camber improves modeling accuracy. Finally, through the comparisons of tire overturning moment between an empirical model and the improved semi-physical model, it can be seen that semi-physical modeling method gets higher modeling accuracy with the same number of model parameters.