Another TST user here. TST system can handle up to 22 tires, so you're still OK! If the repeater is now included, that is something very new. I'm about 40' from furthest tire to monitor, and have no need for repeater. I find the monitor very quick to respond to loss of signal, not an hour as mentioned. Just remove any tire transmitter and the dash monitor alerts immediately. The goal of a TPMS is not to alert in the event of catastrophic failure, but to alert you of a condition that might LEAD to such a failure. Blowouts are a result of low tire pressure, resulting in heat build-up. A TPMS will alert you to dropping tire pressures, usually caused by slow leak/nail in tire, etc., BEFORE it reaches a critical state. This can happen at any point, new tire or old, not just due to age, etc.