civic tire size

I have a 2001 Honda Civic Sedan.I just bought new konig 15 inch rims. I had 4 Dunlop sport A2 installed on the rims. The size of the tire is 205/60R15. I was told by Honda that these tires would be ok for size and also told this at Discount tire where I bought the rims. The problem I'm having is that as soon as I get up to 55mph to about 75mph the steering wheel is shaking badly and lots of vibration.Everything is ok at 50mph. I've had them up to 100mph and everything is ok there also,but still bad between 50-75. Did I buy too big of a tire or is it simply the balancing or ???? I think I should have bought 195/60R15 tires but now I'm stuck with $500 worth of tires that are not performming. Any input would be appreciated.

Balance issue - could even be a bad tire or bent wheel.

That tire size should be fine if nothing rubs, lock to lock during full suspension travel.

The tires don't rub at all and they look terrific on the car. I finally have time tomorrow morning to go back to the store where I bought the tires and I will complain and if nothing gets done I'll be trading them in because I can't stand the vibration. I have traded tires from front to back and I feel there is a problem with more than just one tire.Either that or they just don't wanna work on this car.

i do not think that the tires are responsible for the vibration. check the balancing of all wheels and also check the aligment of your car. i had the same problem with a mitsubishi lancer beetween 110Km/h - 140Km/h. if you still have this problem borrow two rims with two other tires and test the car. If after all the problem is unsolved visit your mechanic and tell him to check your steering system.