Polk’s Top 7 Reasons for Using a Tire Pressure Monitoring System

I think most RV owners have heard stories about an RV that had a tire blowout at one time or another. Some of these tire blowout stories are worse than others, and hopefully if you ever experience a tire blowout it will result in little damage and no one will be hurt.


There is more educational material available now on RV tire care and maintenance than ever before. We are instructed to check and inflate our tires to the correct pressure for the load, not to overload the RV, to inspect our tires for signs of damage and/or excessive wear and to replace tires that show any evidence of damage and at regular intervals.

This is all great advice that should be adhered to, but it is impossible to know what kind of damage may have already occurred to the inside of a tire, and you have no way of knowing when the tire might fail. Another consideration is what might be happening to the tires on your tow or towed vehicle as you travel around the country. Several years ago I had a tire blowout on our towed vehicle and barely noticed it until the entire inner fender was destroyed before I could safely pull over and stop.

This brings me to the topic of today’s article, a Tire Pressure Monitoring System (TPMS). For many years I traveled in RVs without a TPMS. Looking back now I honestly can’t tell you why I didn’t get and use a TPMS sooner. During the time I didn’t use a TPMS I had one rear tire blowout and was fortunate to be traveling at a lower speed when it happened. Even at a lower speed it caused some damage to our motorhome. It wasn’t until we were planning a long RV trip that I decided it was time to look into a TPMS.

I would like to give you my top 7 reasons for using a TPMS on your RV and tow or towed vehicle tires:

1)Most Tire Pressure Monitoring Systems I researched were easy to install and easy to use.

2)It’s a quick and easy way to check the tire pressure in every tire before traveling each day. The TPMS I use is accurate to within 2.7%. That’s as accurate as many tire gauges.

3)You can monitor both the RV and the towed vehicle tires as you travel. That’s what I call piece of mind!

4)A TPMS has an alarm/warning system to notify you of a potential problem. Knowing when there is a potential problem with a tire can limit damage to the RV and quite possibly save lives.

5)My TPMS monitors tires for a loss in air pressure and for possible overheating too.

6)A TPMS can be cost effective. The cost of a decent TPMS can be equivalent to the price of a new motorhome tire, not to mention the damage a blowout can cause to the RV and/or the towed vehicle.

7)I don’t think I was ever as relaxed traveling in the RV as I am now with the TPMS onboard. Driving is much more enjoyable when you know what the tire pressure is at any given time, and the fact that you will be warned if a problem with the tires exists.

As I researched the topic I discovered many reputable companies offering a TPMS that will work on larger motorhome tires. Based on my particular needs and on what I wanted in a TPMS I decided on the Tire Minder, Model TMG 400C by Minder Research

Happy RV Learning,

Mark Polk
RV Education 101
RV University
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RV Tire Tips for Safer RV Trips

It seems as though I talk about tire safety all of the time. The reason I do is because tires are an important safety topic concerning RVers that are often times overlooked.

Just recently I read a newspaper article that summed up just how overlooked tires, in general, are. The article stated, “The Rubber Manufacturers Association found that 29 million drivers believe that tires require no regular maintenance.” This number might be considered small when compared to our current deficit, but it is quite large when you consider 29 million people are driving around the country on tires they don’t know the condition of.

With peak travel season quickly approaching I thought it would be a good time to offer some tire tips for safer trips. These tire tips apply to your automobile as well.

Watch the RV Tire Tips Video

Two of the biggest problems with RVs today are overloading the RV and under inflated tires. With multiple slide-out rooms, large holding tank capacities and the ample amount of storage space available on today’s RVs it’s easy to see why so many are overloaded. We have a natural tendency to fill every nook and cranny of available storage space on our RVs.

Another problem is out of balance loads. You can be within an axle or tire’s load capacity on one end of an axle, and be over capacity on the other axle end. This is a common problem with RVs and many times the cause is poor weight distribution and/or improper loading of the RV. When this happens the tire or tires on the end of the axle that is overloaded are subject to tire failure. The bottom line is overloaded RVs and under inflated tires can be extremely dangerous. The only way to make sure that your RV is not overloaded is to have it weighed.

Weight ratings for RV’s are established by the manufacturer and are based on the weakest link in the chain. When you exceed a weight rating you are overloading one or more components on the RV and risk wearing the component out prematurely or complete failure of the component. In many cases the tires on your RV are the weakest link. Just like the axles on your RV, your tires have load ratings too. The maximum ratings are molded into the side of the tires. Keep in mind these are maximum ratings. The sidewall of the tire shows the maximum load and the inflation pressure for that load. Never set the inflation pressures below the recommendations you find on the vehicle manufacturers placard and do not exceed the maximum inflation pressure ratings found on the tires sidewall.

The tires on your RV are the most vulnerable component affected by overloading the RV. There are numerous reasons for this. First and foremost is when the tires are not inflated properly for the load. Failure to maintain correct tire pressure can result in fast tread wear, uneven wear, poor handling, and excessive heat buildup, which can lead to tire failure.

The only way to correctly measure the inflation pressure in your tires is with a quality inflation pressure gauge. Using your boot, a billie club or a hammer is not accurate, and never depend on your eyes to check tire inflation. There can be as much as 20 PSI difference between tires that look the same to your eye. You need to invest in an accurate inflation pressure gauge. You should get one with a double, angled foot. This makes it much easier to check the outer tire of a dual set.

Check all of your tires on a regular basis and adjust the pressure according to the manufacturer’s recommendation. Never check inflation pressure when the tires are hot. You’ll get a higher-pressure reading and if you let some air out they will be under inflated when they are cold. If you have dual wheels you’ll want to add extension hoses to the valve stems to make the job of checking tire inflation easier. It can be nearly impossible to check the inner dual without extension hoses. The best extension hoses will have stainless steel reinforcement and external braiding for long trouble-free life.

Ozone in the air and UV rays from the sun shorten the life of your tires. It’s not uncommon to see RV tires with low mileage and plenty of tread that are ruined by the damaging effects of ozone and UV rays. Ozone in the air causes tires to dry rot and deteriorate. UV rays from the sun make it happen quicker. This is especially true of the tires sidewall. Inspect your tires for checking or cracks in the sidewalls. If you notice any damage to the tires have them inspected by a professional.

Keep the tires covered with covers that will block out the sunlight when you’re not using your RV. You should also place something like a piece of wood between the ground and the tires. Be sure that whatever you use is larger than the footprint of the tire. No portion of the tire should hang over the edge of the tire block. This can cause internal damage to the tire.

Occasionally washing your tires with soap and water is OK using a soft brush. Sidewall rubber contains antioxidants and anti-ozones that are designed to work their way to the surface of the rubber to protect it. Washing tires or scrubbing excessively removes these protective compounds and can age tires prematurely. The same is true of most tire dressings. Products that contain petroleum, alcohol or silicone are bad for tires.

Tire failure can be extremely dangerous and can cause extensive damage to your RV. There are no
guarantees, but by practicing good tire maintenance you can feel much safer and secure that the weakest link on your RV will do its job while you’re out exploring this wonderful country we live in.

If you would like to learn more about maitaining your RV check out our RV Care & Maintenance DVD

Happy RV Learning,

Mark Polk
RV Education 101
RV University
RV Consumer

Is your Tire Pressure Gauge Accurate?

We often talk about the importance of checking the inflation pressure in tires, but is your tire pressure gauge giving you accurate information? After writing my article titled, “Take the Visual RV Tire Test” I received several emails regarding the accuracy of tire pressure gauges.

One person commented, “I understand that tire pressure in an RV is crucial and can cause serious problems if not inflated correctly. Well, the problem is this, how do you know if the tire gauge is accurate? I have seen two tire gauges show as much as 16 psi difference on the same tire. Is there a recommendation as to which tire gauges are the most accurate?”

What’s funny about this is for many years, as a Maintenance Warrant Officer in the Army, I was responsible for tool calibration programs. Certain tools required regular calibration to ensure accuracy. I use a quality tire pressure gauge, but after reading this question realized that after several years of using this gauge I have never had it checked for accuracy.

Many of the really inexpensive gauges ($5) you can purchase can’t be calibrated, and if the reading is inaccurate the gauge is worthless. This is why you should spend a little more ($15-$25) and get a quality pressure gauge that can be calibrated. I am a real believer in the old saying; you get what you pay for.

If you have any doubt about the accuracy of your tire pressure gauge there are a couple things you can do to check it.

1) You can check the air pressure in a tire with the gauge in question and then check the same tire with another gauge. If there is a significant difference in the readings (4 or more psi) between the two gauges one or both gauges may be inaccurate. If both gauges read within 1 to 2 psi of each other the gauges are more than likely accurate.

2) If you want a more precise method for checking the accuracy take the gauge to a local tire dealer or fleet truck maintenance facility and ask them to check it using a master gauge. A master gauge is a gauge that is certified to be accurate. But I caution you there are lots of tire dealers who don’t have their own tire pressure gauges calibrated.

Note: Don’t depend on pressure gauges at gas stations to be accurate. These are usually abused and neglected, raising concern over accuracy.

There are several different types of pressure gauges available on the market. One important thing to keep in mind is the pressure the gauge is rated for. Most automobile tires are inflated to around 32 psi, so a 0 to 60 psi gauge is sufficient. On the other hand some motorhome tires are inflated to 100 or more psi. It is important, for accuracy and to prevent damage to the gauge, that you get the right gauge for the job. A general rule of thumb is to find a gauge that can read double what the inflation pressure is set at. This isn’t always possible especially with tires inflated to 100 psi, so find a gauge rated for high pressure, like 160 psi.

Possibly the most common type of pressure gauge is the plunge or pencil type. Some of these are calibrated and some of the cheaper ones are not. As a general rule a common plunge type gauge you would purchase will be accurate to + or – 3 psi when it is new. The accuracy of these type gauges are also affected by temperature, humidity and altitude.

Note: Always check the tire pressure when the tires are cold, before traveling. If you check the tires when they are hot you will get a false (higher) reading and if you let air out of the tires they can be seriously underinflated when they are cold.

Like everything else these days’ things are switching from analog to digital. Analog tire pressure gauges were the standard for many years, but advancements in digital technology have improved on that standard. Analog dial gauges are about as accurate as the quality pencil type gauges. In numerous tests comparing different type gauges digital gauges were the most accurate tested.

Regardless of the type of gauge you choose there are high quality and low quality gauges available. Buying a cheap digital gauge would be the same as buying a cheap pencil type gauge. Here are a few things to keep in mind when it comes to tire pressure gauges.

1) Spend a few more dollars and get a quality pressure gauge.

2) If the gauge will be used for checking dual wheels on a motorhome the chuck end of the gauge should have a dual foot design to make the job much easier.

3) Always select a gauge rated higher than the inflation pressure of the tires you are checking. Applying more pressure than the gauge is rated for can damage the gauge and affect the accuracy. If you over-pressure a gauge have it tested for accuracy.

4) Try not to drop or jar the gauge. Store the gauge in some type of protective covering or case and in an area where it won’t be hit or damaged.

5) Periodically have the gauge tested for accuracy. At a minimum compare it to another quality gauge to see if both read the same, or close to the same pressure.

6) Most importantly, once you purchase a quality pressure gauge use it on a regular basis to check your RV and automobile tires.

Remember, properly inflated tires are safer, extend the life of the tires, improve fuel efficiency and lessen the chance of unexpected and premature tire failure.

Happy RV Learning,

Mark Polk
RV Education 101
RV University

Where's the Spare

Why don’t some RV manufacturers include a spare tire with a new RV? Is it a liability issue or a cost issue? I have heard both sides of the story over the years, and it usually depends on what type of a RV you are talking about.

I have owned three towable RV’s and two motorized RV’s. Two of the towable RV’s came with spare tires when I purchased them and I ordered a spare tire as an option on our Class C motorhome, but I could not get a spare for our Class A motorhome.

It seems ridiculous that you buy an RV, designed for traveling all over the country, and the one thing not included is a spare tire. Let’s try to find out why there’s no spare!

It has been rumored that many years ago an RV owner got hurt while changing a tire on his motorhome and that he sued the RV manufacturer. This is supposedly why many motorhome manufacturers opt not to include a spare tire, especially on larger motorhomes.

Admittedly changing a spare tire on a large motorhome is not the same as changing a tire on your automobile. From a liability standpoint the argument is because of the size of the RV and the weight of the tire and wheel it can be dangerous for an individual to attempt changing a tire. Plus you would need to carry some special type of equipment to safely and properly change a tire. I would have to agree, but why not include a spare (without a jack or the other necessary equipment) and have a mandatory warning label stating the dangers of changing a tire along with a recommendation to use a professional road side tire service to change the tire for the owner.

Here is what some RV and chassis manufacturers have to say:

Why doesn't the RV come with a spare tire?

The combined weight of the tire and wheel is approximately 110 pounds. Even if you feel comfortable lifting that amount of weight, other variables pose a problem when it comes to changing an RV tire. You may find yourself on the side of the road in a confined situation, or during the nighttime when it is raining.

Jacking up the side of the RV would be difficult. Leveling jacks are not designed to lift the entire wheel off the ground to change a tire. To change a flat RV tire, it would be necessary to store the correct jacks and jack stands for safety. The next hurdle would be the lug nuts, which are torqued to 500 pounds and difficult to remove. Once removed, and while reinstalling, a tool to properly retorque the lug nuts would be needed. All these necessary tools, combined with the actual spare tire, would take up a considerable amount of space and add additional weight to the RV. Call roadside assistance for tire repair and save yourself the aggravation.

My vehicle doesn’t include a spare tire. Where can I get one and where can I store it?

Most larger motorhomes don't provide a spare for several reasons. Generally, the wheel assembly is too cumbersome and heavy for one person to change alone without risking injury. We'd recommend that, in the case of a flat, you enlist the help of a roadside service crew to fix your flat tire. If you do decide to obtain a spare wheel assembly, contact your dealer for details on ordering one and the proper way to store it.

Now that we know why some motorhome manufacturers don’t include spares why don’t some of the towable manufacturers include spares?

This is where the cost issue comes into play. RV manufacturers look at every penny going in to manufacturing the RV. Not including a spare in the base price of the RV can save money, so they list the spare tire as optional. What this means is when the RV dealer orders the unit they can add a spare or not add a spare. If a dealer is trying to bring a unit in based on price point they limit the options included on the unit. When I was a RV sales manager I included a spare tire on every towable unit just because it made sense and it really wasn’t that expensive.

You still need to consider the safety aspects of changing a tire on a trailer. Even though it’s smaller and lighter than a motorhome tire you still need equipment like a jack, jack stands, lug wrench and torque wrench. In addition to the equipment required, you need to have a basic understanding of how to safely and properly jack the trailer up. But again, if you have a spare you can always call a roadside service to change it for you. If you don’t have a spare you may be stranded in some out of the way place until the tire can be ordered and come in. This could take a couple of days, or longer.

That brings me to how this article came about. We are planning a cross country RV trip this summer and I refuse to go without a spare tire. Our motorhome has 22.5 inch tires with 8 lug rims. When I tried to locate a tire and rim it was difficult to find one. I’m sure I could order one from the manufacturer, but I would be afraid to know what the cost is. We have a good roadside assistance plan so what I decided to do was to just buy the tire itself and if I have a flat the roadside tire service can mount the new tire on the rim. It is less weight to carry and it eliminates the possibility of delays due to ordering and waiting for a tire to come in, if it isn’t in stock.

Regardless of whether or not your RV came with a spare I think it’s a good idea to get one, and I think for safety reasons you are better off having a roadside service plan that will change the tire for you.

What do you think?

Mark Polk

RV Education 101

RV University

Debunking Portable Air Compressors

I think most RVers understand the importance of maintaining proper tire inflation pressure. The problem is if you wait until you’re on the road to check tire pressure the tires are too hot for correct evaluation. Checking the inflation pressure when you stop to refuel doesn’t make sense; you will get higher pressure readings and if you let air out the tires they are underinflated when they are cold. Another problem is when you are at the campground, and you want to check the tire pressure, there is no available air support to do it.

This is why you might want to consider purchasing a portable air compressor. But, air compressors can be confusing to understand, especially if you are trying to find one that is capable of increasing the inflation pressure in large motorhome tires. Let’s start with some air compressor basics.

Air compressors have 3 main ratings associated with them, horsepower (HP), Cubic Feet per Minute (CFM) and Pounds per Square Inch (PSI). Understanding these 3 functions of an air compressor can help us select the right portable air compressor for the job.

We’ll start with horsepower. Unfortunately when it comes to air compressors manufacturers don’t do a great job of explaining it to the consumer, almost to the point some would consider false advertising. Manufacturers tend to over-inflate HP ratings, assuming if the consumer see’s 6 HP advertised, rather than 2 HP, they are more apt to purchase the higher HP rated compressor. This is true in many situations. If you’re a muscle car enthusiast you would definitely consider the HP rating of a vehicle before buying it, right? But if we take a closer look at horsepower, as it relates to air compressors, we can seek out the truth.

Horsepower was invented by an engineer by the name of James Watt. The same watt you think about when buying a light bulb. Watt is used as a measure of electrical and mechanical power. When we apply watts to HP, one HP is equivalent to 746 watts. So if you buy an air compressor rated at 6 HP and it operates on 120 volts it is, in a sense, a false rating. Here is why. If you plug the compressor into a standard 15 amp, 120 volt circuit it would only produce about 2HP (120 volts X 15 amps = 1800 watts).  This is slightly over a 2 horse power rating.

The higher 6 HP rating advertised is commonly referred to as peak HP, similar to a vehicles engine HP rating. The peak HP rating of a vehicle engine is only accurate at a higher RPM range (usually 5000 to 6,000 RPM’s), but rarely do you drive at 5,500 RPM’s. As for the air compressor it would require more amps, from a 240 volt circuit, to produce this peak HP rating.

The Cubic Feet per Minute (CFM) is an important rating when it comes to portable air compressors. CFM is basically a measurement of the rate a compressor can deliver a volume of air. CFM varies with atmospheric pressure. It also varies with the temperature and humidity of the air. Air compressor manufacturers calculate Standard Cubic Feet per Minute (SCFM) as CFM at sea level with 68 degrees F, at 36% relative humidity.

Note: CFM ratings can be skewed by the manufacturer too. Let me explain

Let’s talk about our third rating, Pounds per Square Inch (PSI). For air compressors the CFM ratings are given at a specific PSI. In other words an air compressor rated at 3 CFM @ 90 PSI should be capable of delivering the 3 CFM at 90 PSI. The problem is air compressor manufacturers can advertise a higher CFM at a specific pressure because the air compressor is capable of delivering the rated CFM going from 0 to 90 PSI, but what is the true CFM delivered at 90 PSI. If your air tools or RV tires require a specific CFM rating at 90 PSI you more than likely won’t get it based on the advertised CFM @ a specific pressure. What this translates too is that it will take a long time to inflate some larger RV tires, if the compressor is in fact capable of inflating the tires at all.

When shopping for a portable air compressor the key is to try and find one that can deliver about 4 REAL CFM based on the REAL HP rating at 90 to 100 PSI.

If you have the storage room available, and you will have access to electricity, you can find some reliable pancake style portable compressors that will do a good job inflating tires and performing other small household jobs.

Happy Camping,

Mark Polk

RV Education 101

RV University

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