IMPORTANT - This Listing includes everything you need to monitor the condition of your tyre pressure and temperature. It includes the following parts:

  1. Masten Real-Time TPMS 3.5" Monitor with Upgraded Transmitter and Improved Brightness Panel x 1
  2. Premium Masten TP-09S Internal Valve Sensors x 8
  3. Weather-proof Rubber Seals -fitted
  4. Cigarette Socket Power Adapter x 1
  5. Desk-Mount Monitor Holder Attachment x 1
  6. Windscreen Suction Mount x 1
  7. Masten TP-09REP Range Extender

Spare Sensors:

If you're after spare sensors the part numbers are TP-09S (internal valve) and TP-10S (external cap)



Towing? This clever monitor allows you to 'un-link' when you are not towing so you won't have the monitor beeping while worried about lost sensors. 

Instructions: When the trailer is not connected to the main vehicle, press the LINK and - buttons at the same time. The trailer and its tire icons will be removed temporarily. Press the LINK and + buttons at the same time and the trailer and its tire icons will re-appear. Clever, HUH!



The Masten TP-21 TPMS Tyre Pressure Monitor System with Premium Waterproof Internal Sensors is specifically designed for those wanting to monitor their tyre pressure in a non-obscure way due to the compact design of this monitor.

Key benefits of the TP-21 Masten TPMS

  1. Upgraded 8m Singal Strength compared to similar models 
  2. Improved Screen for greater visibility with intense sun glare with Automatic Backlight
  3. Monitors up to 22 Tyres
  4. Built-in and Rechargeable Lithium Battery with up to 60 hours of charge
  5. Configurable high and low pressure and temperature warnings
  6. Fast Leakage Alert
  7. Anti-theft Sensors
  8. Pressure Range of 0 to 8 BAR (with Â±0.1BAR Accuracy) and 0-116PSI  (with Â±1.5PSI Accuracy) -
    1. For greater pressure ranges (0 to 13 BAR / 0 to 188PSI) see the TP-20 model
    2. Note, this TPMS is also compatible with spare sensors TP-09S Internal Sensors, TP-10S External Sensors and TP-20S External Truck/Caravan Sensors

The TPMS module works silently and alerts you if there is a problem with your tyres. The Tyre data can be viewed at all times. 

Feature List:

  • Professional Installation Required
  • Masten improved the wireless signal
  • Attractive design with visual and audible alarm
  • 50 Metre Wireless Range (line of sight) - With included Range Extender 
  • PSI and BAR Adjustable Units
  • Adjustable Front and rear sensors high/low-pressure alarm range
  • Real-time Tire Pressure and Temperature Display of all Tyres Simultaneously
  • TPMS information screen will automatically appear if a tyre problem is detected
  • The clear display allows you to easily identify problem tyres in red for fast evaluation
  • Premium quality sensors
  • Up to 5 Year Battery Life
  • User-friendly programming functions

Overview of TPMS Monitor and Sensors

  • Monitor Tyre Pressure and Temperature on your Car, Truck, Trailer, Caravan, and Horse Floats Continuously in Real-time
  • The Masten TP-21 Monitor produces an audible alarm when the pressure drops below or rises above your preferred set ranges
  • We have options available for 4, 6 and 8 sensor kits – the TP-21 will pair with up to 22 tyres and we offer spares at an extra charge
  • Easy to use the monitor with a simple switch function allowing you to switch off caravan/trailer sensors when it’s parked 
  • Audible alarm when monitor or sensor batteries are running low
  • Included Cigarette Socket Charger and hard wire cable for concealed power


Masten TPMS Smart Signal Repeater (trailer transceiver)

The Masten TP-09REP is perfect for long vehicles such as caravans, buses, or HGVs with trailers.

A smart relay is recommended to increase the data transmission range from the sensors in the rear tyres. It is normally only required where the distance from the rear wheels to the monitor is more than 7 meters. In this application, it acts as a simple signal booster.

In fleets where trailers are regularly exchanged, the relay is used in smart mode to simplify exchanging trailers. One is fitted to each trailer, where it stores the trailer’s ID and tyre alert settings. When a trailer is connected, pushing a button on the relay sets up a data connection with the monitor in the cab.

The smart relay operates from the 12 to 24V vehicle power supply and is supplied with a fuse-protected connecting lead.



  1. Ensure the stability of receiving signals from sensors when the signal is weak.
  2. Record the sensor’s ID, pressure and temperature limits of the wheels in the trailer and trailer ID.
  3. Support truck and trailer exchange.
  4. Data of sensors in the trailer is transferable between the monitor and trailer exchanger.
  5. Visible and audible alert for high pressure, low pressure, high temperature and fast leakage.

Sleep Function:

If the sensors have not been moved for 1 hour or more they will be in sleep mode. After around 5 seconds of movement, the sensors will 'wake' up and start sending the tyre information data (pressure/temperature) every 6 seconds to the monitor.



  1. Operation as a signal repeater:

The transceiver requires no programming to operate as a signal repeater. The red light stays on while power is connected and flashes while data is being transmitted or received.

  1. Operation for trailer exchange:

Where multiple trailers are in use, a transceiver is fitted to each trailer. Each transceiver is given its own ID and stores the trailer alert settings and sensor IDs.


User Manuals come in the box for the unit and sensors: E-Copies are also available from us. 

We have instructionals on our youtube page also if you are having difficulty installing. 






What are Tyre Pressure Monitor Systems?

passenger vehicles in the 1980s and today is a mandatory feature in the United States. 


Benefits of a Masten TPMS?

The dynamic behavior of a pneumatic tire is closely connected to its inflation pressure. Key factors like braking distance and lateral stability require the inflation pressures to be adjusted and kept as specified by the vehicle manufacturer. Extreme under-inflation can even lead to thermal and mechanical overload caused by overheating and subsequently, sudden destruction of the tire itself. Additionally, fuel efficiency and tire wear are severely affected by underinflation. Tires do not only leak air if punctured, they also leak air naturally, and over a year, even a typical new, properly mounted tire can lose from 20 to 60 kPa (3 to 9 psi), roughly 10% or even more of its initial pressure.

The significant advantages of TPMS are summarized as follows:

Fuel savings: According to the GITI, for every 10% of under-inflation on each tire on a vehicle, a 1% reduction in fuel economy will occur. In the United States alone, the Department of Transportation estimates that under-inflated tires waste 2 billion US gallons (7,600,000 m3) of fuel each year.

Extended tire life: Under-inflated tires are the #1 cause of tire failure and contribute to tire disintegration, heat buildup, ply separation and sidewall/casing breakdowns. Further, a difference of 10 lbs. in pressure on a set of duals literally drags the lower pressured tire 13 feet per mile. Moreover, running a tire even briefly on inadequate pressure breaks down the casing and prevents the ability to retread. It is important to note that not all sudden tire failures are caused by underinflation. Structural damages caused, for example, by hitting sharp curbs or potholes, can also lead to sudden tire failures, even a certain time after the damaging incident. These cannot be proactively detected by any TPMS.

Decreased downtime and maintenance: Under-inflated tires lead to costly hours of downtime and maintenance.

Improved safety: Under-inflated tires lead to tread separation and tire failure, resulting in 40,000 accidents, 33,000 injuries and over 650 deaths per year. Further, tires properly inflated add greater stability, handling and braking efficiencies and provide greater safety for the driver, the vehicle, the loads and others on the road.

Environmental efficiency: Under-inflated tires, as estimated by the Department of Transportation, release over 57.5 billion pounds of unnecessary carbon-monoxide pollutants into the atmosphere each year in the United States alone..

Monitor Specifications

Operational Temperature: -20 to 80°C

Storage Temperature: -30 to 85°C

Transmission Frequency: 433.92MHz

Charger Input Voltage: DC 8 to 30V

Size: 116(L) x 68(W) x25 (H)mm

Weight: 138g


Internal Valve Sensor Specifications - Optional

Operational Temperature: -40 to 80°C

Storage Temperature: -40 to 85°C

Pressure Range: 0 to 8BAR, 0~116PSI

Pressure Accuracy: ±0.1BAR, ±1.5PSI

Temperature Accuracy: ±3°C

Transmission Power:<10dBm

Transmission Frequency: 433.92MHz

Battery life: Up to 5 years

Size: Size: 60(L) x 35(W) x21(H)mm

Weight: 48g

Extender Specifications

Operational Temperature: -20 to 80°C

Storage Temperature: -30 to 85°C

Transmission Frequency: 433.92MHz

Working Voltage: 12 to 24V

Size: 91(L) x 38(W) x 15 (H)mm

Weight: 42g

SKU TP-21-8
Barcode # 9357423020438
Brand Masten
Shipping Weight 0.6000kg
Shipping Width 0.280m
Shipping Height 0.080m
Shipping Length 0.200m
Assembled Width 0.280m
Type Monitor Brightness Panel x 1

2 Year Warranty

1 Year Warranty on Sensors



Changing the Pressure Alarm Ranges

Our TP-19 and TP-20 monitors default alarm settings are as follows:

  • High pressure: 175PSI - NOTE. the Minimum Alarm Range for these models is 3PSI.
  • Low pressure: 100PSI

If you need to re-set the high pressure alert range below 100PSI and find the high pressure setting range is from 100PSI to 218PSI (due to the low pressure setting max. data is 100PSI). This is normal. You will need to set the low pressure first, and then the high pressure again, for example, please set the first axle 1 low pressure to 30PSI, and then set axle 1 high pressure, the high pressure setting range for the axle 1 will be from 32PSI to 218PSI. 

Due to the caravan pressure alert range usually from 30PSI to 50PSI. So please re-set the low pressure of all axles to 30PSI and then scroll to re-set high pressure to 50PSI again. 

Normal re-setting step as below:

  1. Turn on the monitor.
  2. In normal mode, press the SET button for 3 seconds. You will hear a beep when you release.
  3. Press the SET button to scroll through the different settings, the sequence is pressure unit, temperature unit, axle 1 two tires high pressure, axle 1 two tires low pressure, axle 2 four tires high pressure, axle 2 four tires low pressure, axle 3 four tires high pressure, axle 3 four tires low pressure, trailer axle 12 tires high pressure, trailer axle 12 tires low pressure, all tires high temperature.
  4. Press the + or - button to change the setting data.
  5. Press SET button for 3 seconds with a beep to save the new setting.

If you want recover to the default setting, press and hold the SET button without release, then turn off the switch and turn on the switch with a beep. Default setting is restored successfully. 

8 TPMS Tyre Pressure Monitoring System Caravan Truck RV Sensor LCD 4WD Wireless 4x4 TP-21-8 has a rating of 0/5 based on 0 reviews.

Be The First To Review This Product!

Help other Masten Enterprises Pty Ltd users shop smarter by writing reviews for products you have purchased.

Write a product review