The overrun test has been developed to determine road wear caused by studded winter tires. Specially manufactured stones samples are weighted precisely before and after overrunning, the weight loss describing the road wear in grams.
In order to get type approval for a tire and stud combination, the road wear must be below a limit value defined by The Finnish Transport Safety Agency, Trafi. If the type approval is granted based on an overrun test certificate, there are no other restrictions for stud configuration.
Trafi has set parameters and limit values for different load categories, and requirements for studding quality of the test tires. Also, stud protrusion change during the test is restricted. A summary of test parameters and limit values can be found in attached table.