In this paper, a simplified drive train model with stick-slip nonlinearity is introduced for the study of stick-slip motion between the driving tires and the flywheel. Laboratory based tests are designed to investigate stick-slip motion of the tires contacting with the flywheels which simulate vehicle inertia. A description of the powertrain test rig, the associated instrumentation, the test inputs and operation conditions are provided. The experimental results are similar to those obtained from the numerical analysis using the introduced drive train model. They verify the validity of the stick-slip model, and demonstrate that stick-slip occurred frequently between the driving tires and the flywheels. The normal tire force applied to the flywheel is one of the key parameters affecting stick-slip motion. And there exists an upper limit beyond which the tire and flywheel will stick together at all time. It is found that the frequency of stick-slip motion is independent of normal tire force and is close to the natural frequency of the tire-flywheel contacting power transmitting system.