Last year, from CHCH we bought a second hand 2015 Audi A4.
Late last year, a guy who works for a tyre company who walks our dog noticed the tyres had really bad cracking in the middle of them.
I contacted Bridgestone who sent a tech around, confirmed they weren't a manufacturing fault, not specifically a safety issue, but noted they would require careful monitoring and they would need to be replaced within 12 months.
He also noted the date on the tyres were early 2013 but the car was a late 2015 model. He said the reason for the cracking was very likely incorrect storage, either at very high temps or very low.
I contacted the dealer, who predictably wants nothing to do with it, stating it passed both a compliance and WOF and that's his responsibility ended.
My argument is that no-one expects to purchase a 2015 car and have 2013 tyres on it, and having done 16,000 KM, expect to need to replace them.