I’d say you’re barking up the wrong tree.
Why does the seller have any responsibility?
He sold you a set of wheels that you were happy to pay for.
They are not broken or not as described etc, just that you didn’t do enough research before buying them.
A quick ‘ryde 29″ wheels review’ in Google brings up five threads from STW that mention slightly problematic rims and one from Superstar where the chap states he had a mare getting tyres on some Ryde rims.
That alone should have prompted more questions and digging. Blaming the seller is plain daft, and expecting him to send you a tyre is ludicrous.