RV Tires – Tire Pressure; What You need to know
RV tires truly are where the rubber meets the road. Make a mistake here and it cost you more than money.
More people are becoming aware of the importance of the tires on their RV, and watching their tire pressure. Like your car or truck, it is important to keep them properly inflated, replace them when they are worn, but less known is to replace them when they have reached their expiration date. In this article, we will discuss how to determine the correct inflation pressure, how to add air to RV’s with high pressure tires. (Greater than a typical car compressor can deliver.) Lastly, we will look at a system that will help us to predict blowouts, and monitor tire pressure on hard to see tires like dual wheels.
In the above picture, there is an oval on the right with four 1′. All tires by federal law have this oval. The first two digits represent the week of the year that the tire was made. The last two digits are the last two digits of the year. This tire was made the Week of March 12th, 2011. Today’s date is October 5, 2012, which makes this tire about 18 months old. Tire rubber has an average expected life expectancy of 6 Years. This is important for multiple reasons. After 8 years the DOT considers a tire unfit for the road. Should your tire fail and you crash, investigators may charge you for criminal negligence in some states for improperly maintaining your equipment. The very least that would happen in a crash, is your insurance company may absolve itself of liability, leaving you to foot the bill for the crash. (Yes, insurance companies have clauses that say if you brought on the accident via improper maintenance, or criminal activity, they will not pay the claim).
The reason tires are limited in age because of Ozone, and dry rot. This means the rubber begins to disassemble itself. One way you can see how this works is get a rubber band dirty and wet, then set it out in the sun for a few weeks. when you pick up the rubber band, you will find that the elements have caused the band to lose its flexibility, and it has begun to crack. When you stretch the band out, it will snap prematurely. No big deal when a rubber band breaks, but it is a very big deal when a tire breaks when traveling down the road at 55Mph. If it is a rear dually, you risk fire to the RV, as you might not notice the blown tire until it starts smoking. If the tire is a front tire, it can through your RV off of its intended course. Unless you see cracking on the outside of your tires, wait until year number six, have tires dismounted and checked for hidden cracking on the inside. If the tire looks good from the tire guy’s perspective, run them another year or two, but at year 8, replace them.
Having new tires, is not the only thing one must do to make sure his tires are safe. We have to make sure that the tires are properly inflated, and properly loaded. Improperly loaded or inflated tires, are at a greater risk of failure due to heat. If you are traveling in a hot climate, or higher elevations, this problem is compounded.
Tire Loading and Inflation
There will be a sticker inside your RV that looks like the one above. On the left you marked 1. Is the maximum gross Vehicle Weight. GVWR on this RV is 33,000 pounds (Remember that is after you put your things in it. You will find another sticker in the RV that tells you what it weighs with out your things. You can only put the weight difference between those numbers in your RV, no matter how many closets you have not yet filled.)
If you over load the RV, the tires will not be able to support the weight without over heating, and blowing up. Our RV dry weighs at 29,000 pounds, that means we can only have 4,ooo pounds of stuff in it. We currently have 3,500 pounds of stuff, and it does not seem like we brought much. Item number 2, in the image above is how much weight you can have on the front wheels. In this case we can have 13,000 pounds, neither wheel can be loaded over 6,500 pounds. Item number 3, is the Rear wheel weight. We are allowed 20,000 pounds on these wheels, if we were to tow a trailer that put downward weight on the RV, we would have to subtract that weight from the stuff we could place in the RV. This translates to 10,000 per side on the rear of the RV. Since we do not have tandem axles we stop here. If you have tandems, you get a little more hauling capacity, but fewer RV parks possibilities. What we do, is take Our RV up to the public scales to make sure the weight is evenly divided between the four sides of the RV and that we are exceeding the weight limits. In Oregon, we can use the road side department of transportation scales when they closed, free of charge. In other states you may have to pay a truck stop such as Flying J to weigh your RV.
Now that you have your weight set correctly and understand it, the rest is much easier. Item number 4, in the image above shows us what tire pressure the manufacture of the RV has determined will give you the best fuel economy and ride compromise for the size, weight, and type of tire specified for your RV. This RV is supposed to run at 115 pounds in the front tires. (Our tire sidewalls tell us to inflate them to 120, but we follow the sticker in the RV instead. The RV manufacture better understands how the tire is being used.) The rear tires need to be inflated to 95 pounds. Following these instructions should give an acceptably smooth, stable ride, and still yield descent fuel economy. Check your tires pressure before each trip! (Note: The cold tire pressure is rated at an ambient temperature of 70 degrees Fahrenheit.)
Getting air in your tires
These tire pressures are much greater than your local gas station can supply. If you have a smaller RV, requiring only 80 pounds of pressure you can get your air any where. If you have diesel powered RV with air ride, you can run your own air hose from the built in compressor and fill the tires just by running the engine. Some truck stops provide air, but we have found this very hit and miss. A five gallon air compressor brought along with you, or a trip to you local tire store, is about all you can hope for, if you need high air pressure, and you do not have an on board compressor. It is really important that you check your air pressure on a monthly basis, this gauge will accommodate nearly every rig. If your rig has valve stems that are hard to reach, like ours does you might find this unit more usable, but it requires compressed air. Since our rig makes air it works well for us.
Tire Pressure Monitoring System (TPMS)
The last thing you can do to protect your self from tire failure, is on board monitoring of the tires and their pressures. We have experimented with several systems, but only found one we like. We are using Hawks Head TPMS system, which is the same unit as the Tire Minder system. We do not feel the technology is perfected, but yet we use one anyway. The reason we use it, is it will alert us to an air discharge in the tires we choose to monitor. If a dual goes flat, we will know about it before it becomes a fire hazard. These monitors give false alarms due to heat if one side of the RV suddenly gets sun on it, or if we stop some place in the shade. That is small annoyance for the protection they provide. Someday these systems will be perfected. I am very sure of it, as the one that Honda installed in my car is excellent. For now, this is what we have. If you have this TPMS and want to know how to reset to factory defaults, or to set it up, see the instructions at the end of this page.
Hawks Head 22 Wheel TPMS
Monitors the pressure and the temperature of the wheels you decide to monitor. We only monitor the dual wheels, as the flat one may not be seen due to the fact that its neighbor can hold it up.
This is a typical sensor, it has plastic cap, a battery that can be replaced, and the sensor it self. Assemble these pieces, and screw them to the valve stem. It also comes with a locking system, but it is a pain to use, so we never lock the sensors.
The down side of a black plastic cap. Left setting on an uncovered chrome wheel in the Hot Arizona sun, can melt the cap. Then drive to the Oregon spring rain, and you will find your sensors are completely destroyed. We lost two this way.
This is a picture of the valve stem on one of our dual wheels. Place the sensor on the stem and stuff the stem behind the wheel, this will keep the caps from over heating like the one in the picture above. (So we finally learned how to keep our sensors cool)
Buy your Tire minder Here
The repeater – Needed if you are monitoring your car or pulling a trailer over 40′ from the transmitter We found that at 32′ the repeater was needed.
Here is another pressure monitoring system that we have not tried, but would be on our short list id were to replace ours. Here
Programming the System
1. Set the monitor to the factory defaults
TO RESET THE MONITOR, SWITCH THE MONITOR OFF (SEE 26). WE NOW KNOW WHERE WE ARE AT WITH THE POWER OFF. (1) PRESS THE MIDDLE BUTTON TO START THE MONITOR. (2) HOLD DOWN THE 2 OUTSIDE BUTTONS TOGETHER UNTIL IT BEEPS. (3) THE LEFT FRONT WHEEL WILL FLASH AND THE LIGHT WILL BE EITHER RED OR GREEN. (4) IF GREEN HOLD DOWN THE MIDDLE BUTTON UNTIL IT BEEPS AND THE LIGHT TURNS TO RED. (5) IF THE LIGHT IS ALREADY RED PRESS THE RIGHT BUTTON TO GO TO THE NEXT WHEEL (RIGHT FRONT). (6) WE ARE LOOKING TO TURN ANY GREEN LIGHTS TO RED (DELETE THE SENSOR). (7) PRESS THE RIGHT BUTTON AND PASS BY EVERY WHEEL TURNING ANY GREEN LIGHTS TO RED BY PRESSING THE MIDDLE BUTTON UNTIL IT BEEPS. (8) ONCE EVERY WHEEL ON THE MONITOR DISPLAY SHOWS A RED LIGHT, IT MEANS WE HAVE DELETED ALL SENSORS FROM THE MONITOR. (9) THEN HOLD DOWN THE 2 OUTSIDE BUTTONS TOGETHER UNTIL IT BEEPS TO GET OUT OF THE ALIGNMENT MODE. (10) THE MONITOR IS NOW BASICALLY AS YOU PURCHASED IT WITH NO SENSORS REGISTERED.
2. Begin Setting the system up to monitor the wheels you are interested in (Understand Step one above before doing this step)
(1) SET VEHICLE TIRE PRESSURES. (2) SET PRESSURE ON MONITOR (PRESSURE SETTING MODE) TO MATCH EACH WHEEL ON VEHICLE. (3) GO INTO ALIGNMENT MODE AND INSTALL SENSORS ONE AT A TIME (STARTING LEFT FRONT). (4) GET OUT OF ALIGNMENT MODE AND YOU ARE UP AND RUNNING
How prepared are you for your next blow out?
We have covered the basics on RV tires, there are other issues such as to cover or not to cover when parked. There are those that have solid opinions in both camps on that one. Here we only gave the basics, that will help you to stay safe and comfortable on the road. Lastly, no matter how many precautions one takes a blow out is always a real and a dangerous possibility. We will leave you with this video put out by Michelin on how to handle a blow out event. Until next time, keep it real, and stay safe. A roll over in an RV can kill your family! Learn to survive a blow out.