The aerodynamic consequences on wheels due to tyre deformation under operating conditions

The aerodynamic performance of a vehicle is a key attribute that affects its fuel efficiency. The wheels of a vehicle contribute approximately 30% of its total aerodynamic drag, therefore understanding key flow structures is vital in the hopes of improving overall vehicle fuel efficiency. A detailed review has been presented on the operating conditions of wheels as well as the deformation this causes to the contact patch and sidewall of a tyre. This study presents five tyres based off Fackrell's A2 wheel with either centrifugal growth, increased vertical loading or asymmetric loading. It was seen that the growth of the sidewall increases the strength of the two main vortices produced at the contact patch of the wheel. These wheels also saw a reduction of drag by 3-10% and reduction of lift by 11-26%. Increased vertical loading reduced the strength of the two main vortices, with extreme loading restricting their formation. The drag reduction from minor loading was negligible, however lift increased by 14%. Major loading resulted in a drag and lift reduction of 18% and 13% respectively. The wheel with both centrifugal growth and increased vertical loading saw no variation in lift and drag.