The previous owner of my F-27 had done about $1K worth of work to the trailer, and the tires (four plus spare) looked perfectly fine, so I figured he had replaced them or at least they were recent.

I paid a delivery guy to trailer the boat from Florida to Maryland for me. It turned out the tires were old but with little wear to the tread. The trailer blew tires all the way up the coast. Each time added to the delivery cost. After the first one blew I should have told the delivery guy to replace them all at the first chance, but for some reason it didn't occur to me. He said he had thought of it but didn't mention it because he thought I think he was trying to bilk me.

Fortunately no damage to the boat or trailer, but it did drive home a point - trailer tires may look fine, but you have to know their age. They rot just sitting around...