As with all valves a TPMS valve will degrade over time as the rubber perishes or the metal could start to corrode. These will start to diminish the integrity of the valve which could lead to a slow air loss or even a potentially catastrophic air loss.
 
It is recommended that whenever tyres are changed on TPMS fitted wheels that the sealing and fixing components are replaced, which will prolong the life of the valve components.
 
The charge is made per wheel.