I recently purchased a new set of 4 cooper CS4 (P215/60R16) tires for my 2002 Subaru Forester, having them installed by a dealer, along with balancing and alignment. About a week later I crossed the country from Wisconsin to California. On grooved concrete interstate highways, the tires made my car "swim" from side to side erratically. I had to constantly be vigilant to keep the car going straight, and this problem was exacerbated when near large trucks. I assume this is due to the tread design, since I've had two previous sets of tires and never experienced this difficulty. Are tire manufacturers checking their designs on grooved concrete, which is becoming more and more prevalent on interstate highways" is the government checking this issue and working with manufacturers to assure driver safety?" I now have to live with this issue for the life of my tires, which is most unfortunate, and very disconcerting.

- Orange, CA, USA