Summary: Easy to read simultaneous display of max 14 tires, but expensive and other drawbacks.
I've used an
RVi Tire Patrol tire pressure monitoring system for well over 2000 miles now. I drive a 27 foot motorhome with six tires and flat-tow a car. The Tire Patrol displays all ten tire pressures at once in large (5mm) digits on a clear, easy-to-read display. It will display up to 14 tires at once. While driving, one quick glance lets me check all the motorhome tire pressures, and another even quicker glance lets me check the toad.
Tire Patrol consists of a 7-inch tablet, a hub, and the sensors. My tablet says "Designed by Inspira Technologies LLC," made in China. It runs a crippled version of Android. The hub receives transmissions from the sensors on the 900 MHz band. The tablet and hub communicate using WiFi. Mine uses WiFi channel 1 with an SSID that looks like CC- followed by a 12-digit lower case hexadecimal number.
RVi says that because they use the 900 MHz band, the sensors can transmit at higher power than other TPMS sensors using the 400 MHz band, and as a result there's no need for a booster.
Sensors come already labeled and are very easy to pair. They screw on easily. There are no flow-through sensors and no anti-theft features, so they also screw off easily. A sensor weighs 14 grams. Of the ten sensors I bought, one failed to pair. RVi quickly sent me a replacement.
When I placed my order, the RVi web site said this: "When the batteries need to be replaced, you simply mail in your original sensors to the factory and we ship you new sensors for $15/sensor." As of this writing, it still says that, but it's no longer true. Instead, RVi sells new sensors for $15 each, but only if you're the original purchaser and have a receipt. The old sensors are disposable, that is, electronic waste. I hope someone goes into business refurbishing sensors.
RVi says the sensors last 1-3 years, depending on how fanatical you are about removing them when not in use. My current plan is to remove the motorhome sensors if the motorhome will be parked for over a month. However, I plan to leave the toad sensors in place.
The tablet has a capacitive touch screen, which can be a problem when driving. There's a fairly small on-screen button to toggle between pressure and temperature. As far as I can tell, the sensors measure the temperature of the sensors themselves, not the temperature of the air in the tires. Unless a sensor is in direct sunlight, its temperature reading is thus pretty much the outside air temperature, which is not very useful.
A more serious problem is that alerts, such as high pressure alerts, are presented as pop-ups with lots of small (2mm) text. Here's a sample:
High PSI Alert:
High tire PSI detected in sensor(s): RF-4
Pull over at your convenience and check tire(s).
Failure to do so may cause damage.
At the bottom there's an "I UNDERSTAND" button (about 6 x 40 mm) to tap to dismiss the pop-up and silence the alarm.
This is not what you should have to read while driving an RV.
If you wear driving gloves, make sure they have capacitive touch tips.
A good thing about the system is that software can be updated just by connecting the tablet to WiFi. I'm hoping RVi will improve the user interface in a future software update.
My sensors all read 2 PSI high, compared to my hand-held digital tire pressure gauge. This is no problem; I just factor it into the low and high pressure limits.
When parked, it was quite common for the signal from several sensors to be lost. They worked fine as soon as I was moving again. It was different sensors each time, and once working again they showed good signal strength. My motorhome has aluminum sides. This is pure speculation, but maybe I happened to park where tire rotation put a sensor in a bad reception location.
About once a day, signal was lost from a sensor while driving. It always came back in a few minutes.
The tablet comes with a suction mount that works very well.
Like all tire pressure monitors I know of, the sensors measure the absolute pressure of the air in the tires, which is then displayed corrected to sea level. A hand-held tire pressure gauge measures the difference in pressure inside and outside the tire, which is what you care about. At sea level they should read the same, but at high elevation the TPMS will read lower than the hand-held gauge.
RVi support was hard to reach by phone, but they replied to email very quickly.
The hub has a level function. The idea is that, when you're ready to level, you remove the hub from where it's mounted, place it on the floor in the middle of the RV (pointed forward), then bring up the level app on the tablet. This seems like much more pain than gain to me, but if I had a towable RV I might feel differently.
There's a school of thought that one should simply set the pressure alarm limits and never look at the TPMS display. I don't adhere to this school of thought, for three reasons.
First, I want to look for outliers, that is, tire(s) on an axle that read quite a bit different from the rest. Second, I want to look for rapid changes, even though still within the pressure limits. Finally, if a rear motorhome tire sensor fails, I'll temporarily substitute a sensor off one of the front tires. This requires setting the front pressure limits to be the same as the rear, and then monitoring the remaining front tire.
