Think it's the pirelli tyre at the moment with the offer on. I usually get the leaflet through the post once a month with the offers onI think the CostCo £50-off per pair of tyres is still on?
I think I can get four 19" Michelin PS4s for under £600, including fitting but probably not the foamed ones. I have PS3s on at the moment and I am not aware that they are foamed (they are not Tesla marked ones) and they are fine.