A Contact Patch–Based Correlation Framework for Tire Cornering Stiffness Measurements on Drum and Flat Test Rigs

Accurate tire lateral force characterization is essential for vehicle dynamics and handling simulations. Indoor testing is commonly performed on flat track– and drum-based machines, whose different contact surface geometries lead to discrepancies in measured tire forces, especially at low slip angles. This work investigates the correlation between lateral force measurements obtained on flat and curved surfaces, focusing on the low slip angle range, which is representative of typical driving conditions. Cornering stiffness is selected as the key performance indicator describing the linear lateral response of the tire. A physically based correlation framework is proposed, introducing contact patch length as a scaling parameter to account for curvature effects. The possibility of estimating the contact patch length during tire rolling by means of an accelerometer- based smart tire is investigated and compared with static footprint measurement. The methodology is validated on a database of six tires and shows improved consistency between flat track and drum measurements, providing a robust alternative to purely statistical correlation approaches.