Buyer Filed a PayPal SNAD claim for non-eBay sale

[efunc]

I need some basic guidance because this is slightly unusual. I listed 4 car tyres individually on eBay. One of them was sold, but not the rest. The following week I re-listed the other 3. One of these had 6mm tread, one had 6mm tread and a nail embedded in it, and the third one had 4mm tread. All of this was meticulously described with detailed images and measurements. A buyer messaged me asking me if he could buy the 'two 6mm tyres from the set' if I ended the auctions early. I agreed, sent him my PP details and sent the two tyres to him after receiving payment. After receiving the tyres he complained that one of them had a nail in it and filed a SNAD claim, requesting a partial refund.

My question is how do I respond? My auction description clearly highlighted the nail, but I don't think he even looked at the auction. He seems to be confused by referring to the tyre that I sold a week earlier on eBay (visible in my feedback) without a nail stuck in it. However this was not the tyre I had for sale when he emailed me! What does 'Significantly Not As Described' refer to? Is it the eBay auctions I had running that he responded to? Is it some other email correspondence? Because he did not ask me any other questions by email or try to ask for any information or description?

Finally, how does PayPal view transactions that originated on eBay but was then taken off site? Do they regard this as eBay fee avoidance, or ignore it as irrelevant? Since it was the buyer that initiated this would they even throw out their claim?
I urgently require help with this before the buyer escalates the case, so any advice would be gratefully received. Thanks!

[Researcher]

I previously has a customer who said one of the components of my product was faulty, and he escalated it to paypal as a SNAD but upon esclation (buyer escalated not me) paypal reviewed it and went in my favour. This was a claim made within the 45 days

'We have received a complaint from a buyer who stated that merchandise you
sent them did not match your original description. The buyer is disputing
the quality of goods associated with the transaction detailed below.

As you may already be aware, PayPal's Buyer Complaint Policy applies only
to the delivery of goods and not to complaints about the attributes or
quality of goods received through an eBay transaction. Therefore, we will
not conduct an investigation into this matter at this time.'

I guess paypal would take the same aprroach

[JJGold]

Send the buyer an email and try to work things out. If you can't work things out have the buyer ship them back and refund their PayPal.