i just found out after i installed 4 new dunlop winter sport M3's that they are directional. i got 2 right and have to swap the other 2. will this damage the tires?

 

I'm no tire pro, but I don't believe this will damage your tires at all. It may provide you with a bit of a rough ride, but the tires should be ok if they were not on too long.

 

haha yea the ride is somewhat rough. i've only driven 20 miles with them this way and i'll swap them tonight.

 

I remember seeing some sort of road test once where they tested directional tires on a car in both the right and wrong direction. There were very small decreases in handling (slalom speed, skidpad, etc) and small decreases in wet traction, but you'd be surprised at how close to normal they perform.

 

I doubt 20 miles did any damage. IIRC the stock potenzas do better in reverse in the snow.