My listing says " Cash only upon pick up- No pay pal". No postage is offered in the postage tab too.

What part of it is a policy violation to state no Paypal if that is an offered payment method didn't you understand and yes you would be expected to either post or personally deliver the tyre if the buyer chose COD, if you wan to offer cash on pick up then if that option is not showing you need to click on add/remove options and tick the box to display it.

Once again nothing you say in your listing overides the information at the top of the listing where you clearly offer Paypal and COD.

The only way a buyer can get their money back for a pick up item is if they fund the payment with a credit card and then ask the bank to do a chargeback. As long as you take precautions like insisting on photo id with an address and getting the buyer to sign a receipt to say they have accepted then should they try that on you have more than enough evidence to go tot he police and the buyer is unlikely not to remake the payment when threatened with a charge of obtaining goods by deception if it is their card or frwaud if they used somebody elses.