I sometimes get a soft popping sound coming from the front of my XK8. It happens during turns and when going over bumps. Not a very loud sound but noticeable. Is this cowl flex or the shock bushings? Could it also be my wire wheels? I have a set of 18 inch wire wheels (Jaguar with lugs). I know those spokes need tuning from time to time. What would an indication be that the wheels may need tightening up?