People either love or hate 'parcel2go' Andy, with them it would be £20 plus vat (2 parcels of 3 tyres) at £9.99 each.
Most of the complaints are from collection times, but they dont guarantee their specified collection quote time with the standard service (its just a guide).
They do however have a premium guaranteed pick up service which is more expensive. Just depends if the shipper is willing to wait in for them coming, most businesses don't mind as they are there 9 - 5 anyway.