Data-driven development of friction estimators for passenger vehicles is becoming popular. They rely mainly on training data to obtain an accurate estimate of the current road conditions. However, reference or training data for natural conditions containing available friction is sparse. This limits the development of data-driven approaches for friction estimation. The current paper presents progress in a project devoted to developing a method to use standard equipment for road monitoring to acquire reference data for friction estimation, relevant to specific tyres and operating conditions. Results show how a mapping between existing test equipment readings and the real experienced coefficient of friction of a car tyre can be made.