Aside from what may be morally or ethically the right thing to do... In a pissing match, I'd like to have someone tell me how they could legally recover them from my possession. Wheels don't have VIN numbers, unless someone added them as a theft deterrent (you can even have it etched into the glass, but it's not factory)... without the seller admitting to fraud, the wheels belong to the car they are attached to. If the seller makes a legal statement, he puts himself on the hook for the bill and possible criminal charges.
"x" gives (loans) them to "y", "y" sells them to "z"... they belong to "z" unless it can be proven they belong to "x". If the car sold with a title... "z" owns it all legally, any documentation to prove otherwise would also prove "y" is a criminal, and responsible for the theft. Now the buyer can press criminal charges... I wouldn't be at all afraid to stand in a courtroom with a car title I had followed legal process to obtain and let the "stolen property" thing run it's due course.
In my experience, law enforcement would shrug and walk away from this "civil matter" and let the folks straighten it out in court if they wished... I'm not saying it's the right thing to do, just that I'd be inclined to let the seller hold the responsibility for not disclosing prior to the sale.
I also understand smoothing this out, to not damage relationships in our small community. In most transactions, we want everyone to feel satisfied. I know I can be very hardheaded when I fell I've been done wrong, but the battles are seldom worth fighting.
