Fat tyres on T6.1 bike rack

[ndp-camper]

I have just bought a new bike with fat tyres which doesn't fit securely in the tyre shoes on my T6.1 bike rack. Does anybody know of a solution or if you can buy wider shoes please? Are the VW racks made by Thule, and if so what model number? I have looked but can't find any branding on it, except VW.
Thanks for any info.