Evaluating Passenger Car Tyre Performance: Lateral and Longitudinal Dynamics in Varied Testing Conditions

The lateral and longitudinal dynamics of passenger car tyres are crucial for vehicle safety, handling and stability, thus having a direct influence on the braking, acceleration, and cornering performance of a vehicle. This study investigates the influence of key input parameters, namely inflation pressure, vertical load, and inclination angle, on the tyre behaviour using a dual approach: Indoor testing using a Flatbed machine for controlled conditions and Outdoor testing using a traction trailer for real-world evaluations. Lateral dynamics is evaluated across a range of slip angles to analyse lateral force and aligning moment characteristics. The quantification of the influence of inclination angle, inflation pressure, and load on lateral characteristics is done by evaluating the cornering stiffness and aligning stiffness. The indoor tests are conducted in both sweep and steady-state modes. The outdoor tests rely solely on sweep testing due to practical limitations. The longitudinal behaviour is evaluated by measuring the peak friction coefficient, sliding friction coefficient, and longitudinal slip stiffness at various slip ratios to study braking and traction characteristics. To maintain data consistency, all tests use tyres of the same construction and are sourced from the same production batch. The study compares tyre performance during indoor vs outdoor testing evaluation, and steady vs transient behaviour in indoor setups. Compared to the outdoor test results, the indoor test results demonstrate higher brake Mu peak (10-16%) and longitudinal slip stiffness values (30-50%). Across different inclination angles and inflation pressures, the steady state tests showed consistently higher cornering stiffness (up-to 9.1%) and aligning stiffness (up-to 24.1%) as compared to transient tests. The results highlight the influence of test parameters and environments on tyre performance and provide useful inputs for refining testing methodologies and improving correlations between indoor and outdoor assessments.