knocking when decelerating

[passatjimmy]

Ok, this is the issue

On travelling down the motorway, getting up to 65mph, the car starts to shake or vibrate violently, im guessing this is because the wheels are too large for the car but if anyone has any other ideas please let me know

But the main thing is, on decelerating from 65mph onwards, not braking just lifting my foot from the "gas" pedal, there is a knocking noise, very loud, feels like the front wheels are going to fall off, as soon as I accelerate, it quietens down but is still there. Any ideas? The noise comes from both sides, n/s is louder than the o/s and it sounds like something is trapped between the wheel and the arch (which there isn't)

My thinking is its a CV joint or wheel bearing, the car having air ride and the wheels it has its said to possibly eat bearings...so it may just be a garage trip for me.

Let me know your thoughts!

JT