Hi
I have a 2008 A4 Avant 2.0 TDI that's making a grinding noise above 70mph coming from the front drivers side. It kicks in immediately at this speed and stops as soon as you slow back down to that speed. The noise is a rhythmic grinding that get faster the faster you drive. This seems to suggest its related to the tyre but its had new tyres and balancing recently and hasn't stopped the noise.

Audi have had the car but have not managed to work out what the problem is. They suggested it could be the wheel bearing but can't guarantee and its pricey to change if that doesn't fix the issue.

Any ideas before I bite the bullet and spend the money.

Cheers,
Mike.