That's weird.
Winter 2014-2015, my garden cart had lost its air in its four tires. Filling them up again fixed that. After this winter, its four tires are still filled.
Also had to fill up my snow blower's tires at the beginning of the snow season. Its tires are still fine.
My car has a slow leak in one of its tires. And I'm upset as the tires were made in Romania and RRI is one of my favorite stations. In my next reception report to them, I may send them that tire and demand a refund, or at least feature it on one of their upcoming QSL cards. This had better not turn into an international incident.
Something happened in 2015 to cause air to leave tires. I'm going to call my congressman to have him set up a blue ribbon commission to get to the bottom of this.