[Hoggy]

The tyres are fairly new and have plenty of tread.
Although the rear two are 235/35 and the front are 225/35
Could this be the cause? Thanks.

Hi, Those tyre sizes are unlikely to be the cause, unless the treads are "feathering".
More likely wheel bearing, as the humming can be intermittent.
Hoggy.

 

[Hoggy]

Hi norbz93, Had a similar prob on my last VXR, somedays noisy, another day not.
VX replaced wheel bearing under warranty, noise cured. Common prob on original VXR.
Hoggy.