A conventional passenger car is used to measure road adhesion in testing tires. The test track, trie guiding system and the methods of recording measurements are described. Braking in predetermined tracks reduces the well-known scattering of test values considerably. Aquaplaning tests can be carried out independently of wind influences in long narrow stretches of flowing water maintained at a constant depth. Different ways of plotting cornering force versus slip angle show that it is possible to drive straight ahead on a dry, wet or flooded surface with locked steering.