I read the thread on the other forum just now.......he tried to screw you. Period. I only use paypal for online transactions. :( I would reply back that you'd like about $80 worth of wear returned to you in the form of a USPS cashier's check. OR.......he can give you a full refund on the whole deal AND pay shipping back and you keep the tires.
Otherwise I'd say a as$whipping roadtrip is in order :)
I'm dealing with a prick in PA that took my money for an ebay purchase and never sent the product. Paypal told me he now has 4 more days to get back to me or I get a full refund. So we're all getting screwed... :\