(not sure what 'offside wheel' means, passenger side?) Anyway, are you sure it's coming from the wheel and not either the smog pump or the A/C clutch, which will both make the sound you describe when the bearings or clutch starts to fail. Wheel bearings usually just growl when bad, and unless the pads are right down to metal and dragging on the rotor, I've never heard calipers screech like you describe.

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1986 560SL
2002 Toyota Camry
1993 Lexus