RAM truck dashboard showing trailer tire pressure monitoring system display

How Does The RAM Trailer Tire Pressure Monitoring System Work?

How Does the RAM Trailer Tire Pressure Monitoring System Work?

You bought a RAM truck partly because of features like the factory tire pressure monitoring system. The TPMS light on the dash keeps tabs on all four (or six) truck tires. Pressure drops? You get a warning. Simple, reliable, built in.

Now you hook up a trailer. And here's the question most RAM owners eventually ask: does my truck's TPMS monitor my trailer tires too?

Short answer: no. And understanding why — and what to do about it — could save you from the most common towing failure on American highways.

How RAM's Factory TPMS Actually Works

RAM trucks (1500, 2500, 3500) use a direct TPMS system. Here's what that means:

Each wheel on the truck has a sensor mounted inside the tire, attached to the valve stem assembly. These sensors measure tire pressure and temperature in real time and transmit the data wirelessly to a receiver module in the truck. The truck's computer (BCM — Body Control Module) knows the ID of each sensor and which wheel position it's assigned to.

When pressure in any truck tire drops below the threshold (typically 25% below the recommended cold inflation pressure), the TPMS warning light illuminates on the dashboard. Some newer RAM models show individual tire pressures on the infotainment screen.

It's a well-engineered system. For the truck's tires.

The Gap: RAM's TPMS Does NOT Monitor Trailer Tires

This is the critical point that catches many RAM owners off guard.

RAM's factory TPMS is a closed system. The receiver module in the truck is programmed to recognize only the sensor IDs assigned to the truck's wheels during manufacturing or at the dealer. It cannot:

  • Detect or pair with aftermarket sensors on your trailer wheels
  • Add additional sensor slots beyond the truck's own tires
  • Display pressure data from any tire that isn't part of the truck's wheel set

Even if you installed the exact same brand and model of TPMS sensor on your trailer tires, the truck's system would ignore them. The BCM simply doesn't have the programming to handle additional wheel positions.

This means you could have perfect truck tire pressure and a trailer tire at 15 PSI and climbing to 200°F — and your dashboard would show nothing wrong.

Why This Gap Matters More Than You Think

Consider the statistics:

  • 48% of roadside service calls are tire-related. And a disproportionate share involve trailer tires, not tow vehicle tires.
  • 85% of tire blowouts are preventable — caused by underinflation and overheating that builds over miles before the tire fails.
  • Only 44% of tires are properly inflated at any given time. How often do you check your trailer tires with a gauge compared to your truck tires?

Your truck's TPMS has you covered for the tow vehicle. But the trailer — the thing behind you that you can't see, can't feel subtle changes in, and often forget to check — has zero monitoring unless you add it.

And trailer tires are the more vulnerable ones. They run hotter (smaller, higher load percentage, no engine cooling), they sit unused for weeks or months between trips (flat spots, slow leaks, UV degradation), and they give you almost no feedback through the steering wheel when something goes wrong. By the time you feel a trailer tire problem, it's usually already a blowout.

Aftermarket Options for Trailer TPMS

The good news: you can absolutely add tire pressure monitoring to your trailer. The aftermarket has several approaches:

Basic Aftermarket TPMS Systems ($60-$200)

These systems use external cap sensors that screw onto your trailer's valve stems and transmit pressure/temperature data to a standalone monitor mounted in the cab. They work. They're better than nothing. But they have limitations:

Protect your trailer

  • Separate monitor. Another screen on your dashboard that may or may not hold your attention.
  • Tire data only. They monitor pressure and temperature of the tire itself. They don't monitor axle or hub temperature.
  • No bearing protection. A failing wheel bearing generates catastrophic heat in the hub and axle — heat that can destroy a tire from the inside before the tire sensor registers anything abnormal.
  • Limited range. Some budget systems lose signal on longer trailers or in areas with wireless interference.

Integrated TPMS + Axle Monitoring (TrailerWatchdog)

This is the approach we built TrailerWatchdog around — because we saw the gap that basic TPMS doesn't fill.

TWD monitors both tire pressure/temperature and axle temperature. The axle temperature sensors detect bearing heat, brake drag, and other hub-area thermal issues that tire-only TPMS misses entirely.

TrailerWatchdog app showing tire pressure and axle temperature monitoring on phone

All data goes to your phone via the TWD app — no extra monitor cluttering your dash. Set your thresholds, and the system alerts you when pressure drops, tire temperature spikes, or axle temperature rises above normal. You get the warning while there's still time to pull over safely.

Does TrailerWatchdog Work with RAM Trucks?

Yes — and with Ford, Chevy, GMC, Toyota, or any other tow vehicle. TrailerWatchdog is completely independent of your truck's systems. It doesn't need to interface with your BCM, OBD port, or factory TPMS. It's a self-contained system that lives on your trailer and talks to your phone.

This also means if you tow with multiple vehicles (the RAM on weekends, a different truck during the week), the monitoring stays with the trailer. The truck doesn't matter — the TWD system is always watching.

The Complete Picture: Truck TPMS + Trailer Monitoring

The ideal setup for a RAM owner who tows:

  1. RAM factory TPMS — monitors your truck tires. Already built in. Let it do its job.
  2. TrailerWatchdog — monitors your trailer tires AND axle temperatures. Fills the gap that the factory system can't.

Together, you have continuous pressure and temperature monitoring on every tire and every axle in your rig — truck and trailer. No blind spots.

For more on maintaining proper trailer tire pressure, see our trailer tire PSI guide. If you're upgrading wheels and wondering about your TPMS sensors, check out how to move TPMS to new wheels. And to understand why tire temperature matters as much as pressure, read how hot should a trailer tire get.

Related Reading

Your RAM Monitors the Truck. Who Monitors the Trailer?

The TWD Adventure ($395) covers most trailers with combined TPMS + axle monitoring. For heavy-duty towing or multi-axle rigs, the TWD RoadCommand ($595) provides expanded coverage with more sensor capacity.

Both work with any tow vehicle. Made in America (Ijamsville, MD).

See the TWD Adventure →

Or explore the TWD RoadCommand for heavy-duty setups →

Frequently Asked Questions

Does my RAM truck monitor trailer tire pressure?

No. RAM's factory TPMS only monitors the truck's own tires. The system cannot detect, pair with, or display data from trailer tire sensors. You need a separate aftermarket system to monitor trailer tires.

Can I add trailer tire sensors to my RAM's TPMS?

No. The RAM's Body Control Module (BCM) is programmed for a fixed number of sensor IDs — one per truck wheel position. It cannot be expanded to include trailer wheel positions. Even using identical sensors on your trailer won't work; the BCM will ignore them.

What is the best TPMS for a RAM truck towing a trailer?

For trailer-specific monitoring, a system that monitors both tire pressure/temperature and axle temperature provides the most complete protection. TrailerWatchdog is the only system combining TPMS with axle temperature monitoring in one package. It works independently from your RAM's factory TPMS, so both systems complement each other.

Does TrailerWatchdog replace my RAM's TPMS?

No — and it shouldn't. Your RAM's factory TPMS monitors the truck tires; TrailerWatchdog monitors the trailer tires and axles. They serve different roles and work together to give you complete coverage across your entire rig.

Will TrailerWatchdog work if I switch tow vehicles?

Yes. TrailerWatchdog is installed on the trailer and communicates to your phone via the TWD app. It's completely independent of the tow vehicle. Switch trucks, and the monitoring stays with the trailer.