Audi A3 Funny Noise

[sir jonny]

My mate has as A3 (51 plate, 60K, after market wheels) and it has started making a vibration type noise.

It is loudest at 40 and 60 but is there all of the time. It does not just get louder the faster you go.

It is the same regardless of which gear it is in or whether the clutch is engaged.

Braking and steering have no effect either.

Any ideas???

[sir jonny]

The brakes and steering work fine and other than the change caused by changing speed they have no effect on the noise.

[sir jonny]

Don't know if the wheels were balanced, they were on the car. The steering wheel does not vibrate, you can feel it far more if you touch the floor.