Anyone have any experience of this rack will take fat bike tyres or do I need to look elsewhere??.. Thanks.. ??

I believe you can buy thule fat tyre attachments

on my G5 I just use short ‘tie down’ type straps (these: http://www.roofbox.co.uk/straps/fasty_straps_range.php
) to hold the wheels onto the wheel holders – they don’t rest in the wheel groove so much as other tyres but they#ve not moved whilst driving.