Passenger side wheel sounds like steam train

Today the passenger side wheel started making a noise I can only describe as a steam train or a little like a flat tyre. It only does it while coasting, if you accelerate or break that noise goes away but once you coast again it starts. Had my wife drive the car slowly while I could look in the arch. Nothing noticed, at first when in the arch I though it sounded like the spring could have gone and was grinding but didn’t look like it. Anyone any idea why it would be making the noise while coasting and not while accelerating or breaking and what it could be?

You should say whether its front or back and what model it is.

I take it you do not think it is a metalic type sound.

Have you checked that the 4 tyres are pumped to the same pressure?

Front it's likely to be the brake splash guard has rusted and is rubbing on the rotor.
Rear it's likely to be the backplate splash guard has rusted and is dragging on the drum.

It’s the front passenger sorry.

when the cars moving really slow it would almost like a creaky spring. When inside it just that steam train effect. Just strange it stops when accelerating and breaking?