I realise this has been done a few times before...But mainly on Gen 2 XC70's

So - the G3 XC70 has 63.4mm hub centres, and 55mm offset.

The XC90 wheel has 67.1mm hub centres and 49mm offset.

You can easily buy 67.1 / 63.4mm "spigot rings" to amend the hub diameter (only £5 in UK).

Regards the offset - is 6mm enough to cause a problem? I'm sure you could easily fit slightly wider tyres, so I'm sure there's enough clearance...will 6mm really affect the handling?

Keen to hear your thoughts...