What TPMS Sensors Do I Need for My Trailer?

Choosing the right TPMS sensors for your trailer isn't complicated — but picking the wrong ones means wasted money and no protection when you need it most. With 85% of tire blowouts being preventable through proper monitoring, getting this decision right matters.

This guide breaks down the types of TPMS sensors available, what's compatible with your trailer setup, and what features actually matter versus what's just marketing noise.

The Two Main Types of TPMS Sensors

Internal (Valve-Stem Mounted) Sensors

These replace your standard valve stem and sit inside the tire. They're the type that comes factory-installed on passenger cars and trucks. For trailers, internal sensors have significant drawbacks:

• Require tire dismounting for installation and battery replacement
• Must be professionally installed
• Adding or removing sensors means a trip to the tire shop
• Not practical for trailers with seasonal tire swaps

External (Screw-On) Sensors

These thread onto the existing valve stem from the outside. They're the standard for aftermarket trailer TPMS systems because:

• Install in seconds — literally screw them on
• No tire dismounting required
• Easy battery replacement on most models
• Can be moved between trailers or tires

Magnetic (Non-Contact) Sensors

The newest category — sensors that mount magnetically to the axle hub or wheel assembly rather than the valve stem. These monitor axle temperature in addition to tire pressure, providing dual-point failure detection. The TrailerWatchdog TWD-1500 uses this approach, combining TPMS with axle temperature monitoring in a single no-drill, IP67-rated package.

Sensor Comparison Chart

Feature	Internal (Valve-Stem)	External (Screw-On)	Magnetic (Hub-Mount)
Installation	Professional required	DIY — 2 minutes	DIY — magnetic snap-on
Battery replacement	Requires tire dismount	DIY — replace coin cell	Varies by model
Theft risk	Low (hidden inside)	Moderate (visible, use lock nuts)	Low (magnetic grip + position)
Accuracy	±1 PSI	±1–2 PSI	±1 PSI
Monitors temperature	Tire air temp only	Tire air temp only	Axle temp + tire pressure
Waterproof rating	N/A (inside tire)	IP65–IP67 varies	IP67 (TWD-1500)
Best for	Permanent installations	Most trailer owners	Maximum protection

What to Look for When Buying TPMS Sensors

1. Wireless Protocol

This determines range, reliability, and battery life. Here's how they stack up:

Protocol	Range	Battery Life	Signal Reliability
433 MHz RF	15–30 ft	2–5 years	Poor through metal
Bluetooth 4.0	30–50 ft	1–2 years	Moderate
Bluetooth 5.0	100+ ft	1–3 years	Excellent

For trailers, Bluetooth 5.0 is the clear winner. The distance between your cab and trailer axle can easily exceed 30 feet on a travel trailer or enclosed cargo hauler — and that's in a straight line without accounting for the metal walls and cargo blocking the signal.

2. Number of Sensors Supported

Count your tires, including duals:

• Single-axle utility trailer: 2 sensors
• Tandem-axle travel trailer: 4 sensors
• Triple-axle fifth wheel: 6 sensors
• Tandem with duals (cargo trailer): 8 sensors
• Tow vehicle + trailer combo: 6–12 sensors total

Make sure your TPMS system supports enough sensor positions. Some budget systems max out at 4 or 6 sensors.

3. Pressure Range

Passenger car TPMS sensors typically max at 50 PSI. Trailer tires commonly run 50–80 PSI, and some run up to 110 PSI. Verify the sensor's rated pressure range covers your tires. Using sensors rated too low will give inaccurate readings or fail to register at all.

4. Temperature Monitoring

Basic TPMS sensors only measure air pressure inside the tire. But bearing failures and brake drag show up as axle heat long before they affect tire pressure. A system that monitors axle temperature catches an entirely different — and equally dangerous — failure mode.

5. Alert Method

How does the system tell you something's wrong?

• Standalone display: Mounts in cab, audible alarm. Simple but adds dashboard clutter.
• Smartphone app: Alerts on your phone via Bluetooth. More detailed data, no extra hardware in the cab.
• Both: Some systems offer dual alert paths.

6. Waterproof Rating

Trailer sensors live in a brutal environment — road spray, rain, car wash bays, stream crossings. Look for a minimum of IP65 (water jet resistant). IP67 (submersion rated) is ideal for boat trailers and any trailer that sees wet conditions.