Constant, real time tire pressure monitoring: hopefully improved blowout protection

[RockyMtnRay]

One of my biggest worries when towing is having a blowout on a trailer tire. Not only do blowouts cause substantial delay but if the streetside tire is the one that blows, there's a real good chance the disintegrating tire will severely damage the drain pipes. And a blowout on either side can do substantial damage to the floor and even innards of the trailer. And worse yet, about 60% of my towing is over narrow secondary and even tertiary highways that usually have absolutely no shoulder to pull off on...and turnoffs/driveways are often miles apart!

So I glean everything I can about trailer tire blowouts. It seems the consensus among tire experts is that about 90% of all blowouts are due to underinflation. The underinflation can be just plain low pressure or insufficient inflation for the load being carried. The other 10% are often attributed to tire oxidation (aka dry rot), road damage to the tire structure, or sometimes just plain loss of strength due to high mileage. Good storage practices, avoiding road damage as much as possible and replacing the tires every 5 to 7 years, apparently go a long way to prevent the non-underinflation causes. And I do all this, including storing the trailer inside my garage and taking the trailer's weight off the tires during storage (so there won't be a sidewall bulge during storage).

And I keep my trailer tires inflated to exactly 50 psi and check that pressure at the start of every towing day. But so do a goodly number of other folks...and many, like our member/moderator Bill...have had blowouts nonetheless. And more importantly, apparently many of those blowouts occurred with a very hot, probably severely underinflated tire: the clue is the mention of substantial amounts of rubber that were very firmly stuck to the trailer from the blowout. IMO, the only way that rubber is going to stick to the trailer's skin that firmly is if it was nearly molten when the tire disintegrated.

My conclusion is a tire that blows from underinflation yet was properly inflated at the start of that day had to suffer some kind of damage that started a leak. And all it would take is to run over a sharp object...nail, piece of junk metal, etc. And I further concluded the way to prevent a underinflation caused blowout resulting from a leaking tire was to install a system that constantly monitors the pressure in both trailer tires and instantly reports a pressure drop, even small, to a monitor in my truck's cab.

So I invested in a tire pressure monitoring system from Doran Pressure Pro . For $290, I got the system monitor and 2 sensors for my trailer's tires (the monitor can handle up to 16 sensors so I could add additional sensors for my truck's tires whenever I want to...additional sensors are $50 each). In a nutshell, the system works as follows:

• Each sensor sends a coded signal; during setup of the system you correlate a given sensor with a tire position on your rig. If there's a pressure loss, the monitor will identify which tire has the problem.
• When you screw the sensor on the valve stem, the pressure it records at that moment is its baseline pressure. As long as the pressure does not drop more than 12.5% below that baseline, the sensor sends out a pressure report about every 5 minutes. You can therefore get a reasonably current (within 5 minutes) display of each trailer tire's pressure at any time by pressing the up/down buttons on the monitor. Good for piece of mind...and pretty much precludes having to actually check the pressure of each trailer tire with a gauge every morning.
• If any tire's pressure drops 12.5% or more below the baseline, the sensor on that tire starts sending out signals every second or so...and the monitor displays a warning light and emits a warning sound. If the pressure drops 25% or more below the baseline, the monitor emits more urgent warnings. Clearly the smart thing to do is to get pulled off the road ASAP after the first warning sounds.

After using the system for about 1200 towing miles, I'm very happy with it even though there have been no pressure losses from my trailer tires. It's quite interesting to monitor the tire pressure changes that come from both changes in air temperature during the day as well as the temperature changes from towing speed changes (e.g. going from 50 mph to 65 mph seems to cause about a 2 psi increase in pressure). Although the sensors weigh about 2/3 of an ounce...and I did not have the tires rebalanced to accommodate that weight...I've had no indications of imbalanced tires. About the only effect I'm seeing is that the sensors are slightly bending the rubber valve stems at speed...you can see rub marks from the sensors on the wheel rims in the photos below.

Pictures:

• Pic of the monitor sitting on my truck's console...it's about the size of a typical rear view mirror. When towing, I usually just put the monitor on the console; when not towing I stow it inside the console's bin.
• Closeup pic of the monitor after I pushed a button to cause a pressure display of one tire's pressure. The tire being checked had a pressure of exactly 50 psi that morning (at a temperature of 70 degrees); after a few miles of towing (at ~45 mph) on a 90 degree day, the pressure rose to the displayed 54 psi.
• Pic of one of the sensors relative to the whole wheel.
• Closeup pic of the sensor. I put the label on the sensor so I know which tire it's associated with in the monitor. To increase sensor battery life, I plan to remove the sensors during winter storage...if they're not detecting any tire pressure, they stop transmitting.

Any questions???