Thanks for all the tips guys, very useful. I will be looking into it this weekend.

Alex

 

I didn't see one thing that might be the problem. Wheels are balanced and you may have lost a balancing weight.

 

Are you suggesting that "City" driving will be affected by a unbalanced tire? An unbalanced tire usually causes a vibration and rarely felt under 55 MPH.

 

^ True, it wouldn't be a balance weight issue giving him a "metal knocking sound" at slower speeds like that....unless you have stick on weights and one is hanging down and dragging on the caliper. If not that, then I'm putting in my vote as loose lug nuts being a possibility too. I've had that happen, but it did make the steering wheel shake a bit as well.