TPMS
Direct
Indirect
Mandatory in most of the world since a few years
Type
Stem mounted
Band mounted
Inner tire
Operations
ABS monitors the wheel speed
It helps out the indirect TPMS system as well
Will roll at a varied wheel speed
When the tire pressure drops in the tire
Computer system notices makes the low-pressure light come on
Operations
Sensors measure temperature and pressure
Send data to the vehicle regularly (with sensor ID)
Alarms event when necessary
Advantages
More accurate
Advantages
Disadvantages
Needs reset after tire inflation and rotation
Less expensive than a direct TPMS
All four tires are deflated could be not detected
Disadvantages
Sensors can be damaged during installation
Costlier than indirect TPMS
Installation needs professional help
Sensor batteries can run down
No need to reset after tire inflation or replacement
Provide also temperature
Low maintenance
Installation can be one at home
Reading not highly accurate
Real time measurements