Hi All

I have just purchased a Merc 230 CLK Kompressor 1999 on the V plate, the car is a real gem and has full Merc service history, I have noticed at a speed of say 20 to 25 mpg I have a slight humming noise coming from the front of the car ???? the car has 18" alloys with new tyres on could it be these that are making the noise ??? I have spoke to the main dealer who have recently serviced the car and the only thing that needs replacing from the service is a off side ball joint, any ideas what the humming noise could be

Russ