Abstract: A system for improving the power of vehicle wheels on a support, e.g. a winter slippery surface, has nozzles near the wheels supplied with a sticky or tacky liquid from a container under the control of the driver. The container is connected with a doser and with a source of compressed air, e.g. compressor, which is used for both application of the liquid to the wheels and cleaning the nozzles. The system includes a dosing reservoir and a three-way valve, the container being connected with a first branch of the valve, the dosing reservoir being connected with a second branch of the valve, nozzles being connected with the third branch of the valve. A first conduit extends from the compressor to the reservoir for application of the liquid and a second conduit extends from the compressor to the nozzles for cleaning the same. Alternatively, dosing may be carried out by the aid of time controlled dosing directly from the container and time controlled supply of compressed air to the nozzles.