I have a set of aftermarket rims on my A4...after about 7000 miles, a considerable amount of vibration is felt in the car from 65 to 70 mph. If I go faster or slower, it subsides. I went back to stock for the winter and the vibration is totally gone. Will rebalancing the aftermarkets correct this problem or will it continue to get worse? Any insights will be appreciated.

Two things can cause this. Out of round or out of balance. Try the balance first as when on the machine one can watch for out of round condition. Radial force variation in the sidewall acts like out of round but can not be seen nor checked on most balancers. If running non-OEM wheels, make sure they are hubcentric. The lugs are to hold the wheels on not center it. It is not uncommon for a newly mounted and balanced tire to go out of balance after accumulating some miles. Start with the balance.

99% case is the wheels are out of balance. A vibration that occurs at a particular speed is usually the cause of incorrect wheel balance. Perhaps a weight fell off. Happens all the time especially in snow, ice, or mud conditions.

Thanks for confirming my thoughts!