The term "intelligent tire" describes tires equipped with sensor systems to monitor thermal and mechanical parameters while driving. Information about temperature, tire pressure, tread wear, etc., is collected and used for car operation and maintenance support. The contact between tire and road surface is a key parameter when characterizing the ability to accelerate, decelerate and steer a vehicle, therefore making contact monitoring important for modern car control systems. Following numerous previous theoretical works, the friction coefficient can be measured by evaluating the mechanical strain in the tire surface contacting the road-utilizing the deformation of the tread elements. A new monitoring method using passive radio requestable SAW sensors is presented. The principle, measurement setup and experimental results are shown.