1. A method of determining a future heading of an object, the method comprising: receiving, by one or more processors, sensor data including information identifying an object in a vehicle's environment and sensor data points corresponding to the object; identifying, by the one or more processors, an area corresponding to an expected location of a wheel of the object based on the sensor data and a model of wheel locations; estimating, by the one or more processors, an orientation of the wheel based on the sensor data points having locations within the area; and determining, by the one or more processors, a future heading of the object based on the estimation.