Our Prius got four slow tire leaks over the last year. During that time, the tire pressure warning system (TPMS) also stopped working. As a result, the last leaks were discovered only when the tires were visibly and dangerously flat. Andy at George Oren Tire looked at the tires and said they had plenty of tread left, but we really wanted the warning system working so we could drive with confidence that the leaks had been stopped. The alternative was constantly checking the pressures manually. We supplied replacement TPMS sensors (which had been acquired online) and Orin put them into the 4 wheels and re-programmed the system for $65 total. Now the waring system is monitoring the tires for us, and we can trust the tires until they are finally worn out. When it is time, we plan to get new tires from Georg Oren.
Doug, at the Oakland location, was also very helpful when he replied to an email by calling me to discuss the options.