Right so took my car to the garage this morning and the mechanic took it for a drive down the motorway with me in the car.
As we drive you could hear the humming sound at a constant level which he said is tyre noise. Also when slowing down I advised the noise gets louder but he said it will do with the tyre noise but then when you slow right down and drive there was no noise. He said if it was wheel bearings then the noise would be constant and would also change when turning the wheel but the noise I had did not.
He said he noticed the noise was louder but I advised I had swapped the rear tyres with the front so he advised it is likely the previous rear tyres which are now at the front which are making the noise. He said it sounded more like the drivers side too.
He did say you will get more noise with budget tyres and I have listed mine below which on googling all look like budget makes but he said to check the speed rating to make sure you have the correct rating. One of my tyres says W88 and the other 3 say 92W which I think is fine.
Front Drivers - 225/40 ZR18 W88
Front Passenger and both Rear tyres - 225/40 ZR18 92W XL
What I did notice is all of my tryes apart from the Front Drivers look quite inflated but the Front Drivers does look a little flatter so maybe that could be contributing to the noise.
Does anyone know where I can fine what the PSI should be for the above tyres sizes on my Golf MK 1.4 TSI
Having mismatching tyres won't help either 
No it probably will not but these tyres came with a set of cheap alloys I got and never had any issues until in the last month
Checked online and got the pressure of 29PSI all round. 2 tyres were 28PSI, one was 32PSI and the front driver was 25PSI
Pumped them all up/down to 29PSI and drove home from garage and the noise is definitely not as loud but can still hear and does sound like the front drivers side now. I am going to swap the Front Driver with the Rear Passenger and if the noise is a lot less then be done with it and just drive them until they need replacing and then get myself a good set of tyres.
At least if it turns out to be tyres which it is looking like then there is no issue with the car apart from cheap tyres of course
