If this is your only User ID you need to learn how ebay works fast. I imagine the seller has paid substantial fees and won't be happy.
If you can't wait a few days then that sounds like an excuse. Have you found out the tyres will be delivered by courier or freight and it will be expensive ? You need to allow for that when you buy an item that can't be posted. Don't be surprised if you receive a strike from ebay for not paying.
