Partial aquaplaning disrupts handling by boosting aligning moments (Mz) while reducing cornering stiffness (Cy), complicating steering feel. The study extends TreadSim to model hydrodynamic pressure, variable normal-load distribution and contact patch deformation, capturing tire-road behavior in water. Simulations across water-film thicknesses and speeds show Mz rising from hydrodynamic forces and Cy falling as lateral force transfer weakens. Force-hub experiments validate trends and magnitudes, supporting model reliability. Elevated Mz can mask low-friction conditions, delaying driver recognition and response. Integrating these dynamics into steering feedback and driver assistance algorithms can enhance detection, intervention and safety. Ultimately it improves vehicle stability and driver confidence.

• How partial aquaplaning shifts tire forces: Mz rises while cornering stiffness drops
• Why elevated Mz can mask low-friction and mislead steering feel/driver response
• How to add to TreadSim hydrodynamic pressure, load redistribution and contact-patch deformation