1. The Scandinavian Tire & Rim Organization Directional Tyres Two types DirectionalDirectional and asymmetric

2. The Scandinavian Tire & Rim Organization The tyre is made directional because the producer wants some special performaces which is not possible to get with a standard tread design. Can be: winter performance, water drainage etc. The intended rolling direction is marked on the sidewall

3. The Scandinavian Tire & Rim Organization Two possibilities to mount the tyre

4. The Scandinavian Tire & Rim Organization Main problem: It’s possible to mount the tyres in the opposite direction compared with the direction intended by the tyre producer and the markings on the sidewall.

5. The Scandinavian Tire & Rim Organization This is not forbidden, but not recommended. The tyre performace will not be the performace intended by the tyre producer. This is not a danger to safety.

6. The Scandinavian Tire & Rim Organization Conclusuion: Allways mount the tyre in the intended rolling direction. Look for the arrows on the sidewall. If you find a tyre mounted in the wrong direction, this should be rectified a.s.a.p.

7. Reflections: To change the tyre brand or even to change tyre type within the same brand have bigger effect on the performance of the car than to mount the tyre in the wrong direction. To change between summer and winter tyres have bigger effect on the performance. To use a temporary spare tyre have more negative effect on the car performance To use a worn tyre has bigger effect on the performance. All these facts are well known but are not discussed as a safety risk. The Scandinavian Tire & Rim Organization