How often do they change the tires on a USPS mail truck? "Just like any vehicle, eventually, a USPS mail truck will need its tires replaced. But, just how often does that happen? Currently, the Postal Service’s Postal Vehicle Service (PVS) has two contracts out that handle tires. One contract to purchase tires that are new, and another contract to buy tires that have been retreaded. It is important for mail trucks like the Grumman LLV to have healthy tires. That way, mail carriers can successfully make deliveries."