noise from rear wheels

Hi all , had some new tyres put on the back and they do kick up a lot of road noise but have noticed at 65-70 (just before it dies but that is another story ) that I get a moaning noise that comes and goes every couple of seconds , sort of builds and then goes quiter and then builds and so on , any ideas guy's ?

atvb Paul.

p.s. it did this with the old tyres but is now really loud , before you could only just make it out and I put it down to the road surface . Was hopeing the new tyres would improve it not make it worse .

Rear wheel bearings should be first on checklist. My offside rear had gone and it sounded like the whole diff / drivetrain was about to retire. One new wheel bearing later and she is back to normal i.e never as quiet as a 2 wheel drive car but great for an FL. Regards.

Thanks , will get it checked .

atvb Paul.