Higher Mileage and Inflation; Hold the Nitrogen July 20, 2009
When it comes to gaining higher mileage in today’s cars, are auto makers using off-the-shelf technology to their best advantage? Has all of the proverbial “low hanging fruit” been picked when it comes to getting the best vehicle mileage possible? Or is all we have left some new, pie in the sky innovation that will cost a fortune and require totally new infrastructure?
I believe the answer to all three of these questions is, “No.” If auto manufacturers would be willing to rethink which options they reserve for high-end vehicles and make some of them more mainstream, there is at least one current technology that I believe could help make a useful difference.
Several months ago a good deal of sarcasm and ridicule occurred between politicians in the national media when it was suggested that one thing people could do to improve their mileage would be to check their tires for proper inflation. Mind you, the sarcasm was based on suggestions that this could be part of a national energy plan to reduce dependence on foreign oil. As a cure for our nation’s long-term energy needs, this is certainly NOT the answer. At the consumer level however, based on what’s left in our wallets at the gas pump, this matter should be considered more seriously. The concepts are simple.
Low tire pressure increases rolling resistance, and is bad for fuel economy. Higher tire pressure reduces rolling resistance, which improves fuel economy. These issues are all-too-often ignored, and there is something that could be done to remedy the situation.
Vehicle manufacturers could use this to their advantage by selling it as a worth-while fuel saving feature, while it also helps improve safety and extends tread life on tires. It represents a win-win scenario all around.
What is this feature? If the same on-board Tire Pressure Monitoring Systems (TPMS) and inflation technology that has been used on some Cadillac models and the Chevrolet, Corvette, were offered as standard equipment on other new vehicles, fuel economy and tire life could be extended considerably over the life of every vehicle using them.
Some of these systems not only monitor the tire pressures, they also adjust the inflation to the proper level while the vehicle is in use. From the factory, these are top-of-line (and costly) systems to be sure, but there are far less costly ‘monitor only’ systems that can warn drivers that their tire pressures are in need of adjustment, and this alone would go a long way to alert the public of the need. If drivers were clearly informed on their instrument panel that a tire pressure adjustment should be made, while being told which tires(s) need more inflation, and by how much, it would put very useful information in the public’s hands, so individuals could better make their own fuel consumption and tire life choices.
If people want to maximize their fuel economy, they would make the needed adjustments based on the information provide. They could then take comfort in knowing they are doing what’s best for their pocket book and vehicle’s performance. When this kind of information is only available through the use of a tire gage on all four tires (don’t forget the spare), history tells us the public is not apt to bother due to the inconvenience. These days we are warned when less important things like the washer fluid level is getting low, so why not tire pressures?
Sad as this seems, when modern vehicle owners are not warned that something needs attention, maintenance becomes far less likely to be addressed. Even WITH warnings, most of us know folks who have kept driving a vehicle after they were clearly alerted of a problem. These cases aside, when there is no warning at all that a mechanical or electrical problem exists there is obviously room for improvement. Self monitoring systems take all the guess work out of the correct tire pressure issue. Just like the information provided by your vehicle’s gas gauge, when users are aware that the fuel level is getting low, they are far more likely to act on the information than if no information were provided at all. There is no reason we should be left in uninformed when it comes to modern vehicles tire pressures.
Only the manufacturers can decide whether to offer these systems, but they base those decisions in-part on what the customers ask for. If the public fails to ask for an option, it becomes a hit-and-miss situation whether the manufacturer’s marketing department might be aware that this feature would be useful on more than their upscale vehicles. The logic may miss them entirely, that this feature would be useful on more modest vehicles. Like any mass marketed product, the more a feature is used, the less expensive it becomes.
A word of caution needs to be addressed here. Beware of tire pressure "snake oil" salesmen.
In the wake of gas prices going higher and higher, a number of schemes have cropped up to try and convince consumers that better mileage can be had by using some ‘race proven’ products and services.
One of these schemes that I feel should be looked at with a critical eye is tire-inflation services that some places are offering, which for around $30 will fill your tires with nitrogen.
Why would anyone pay thirty dollars to fill their tires with the same gas that makes up 78% of the air we breathe? Without getting too technical here, the gas laws of Physics tell us that all gases act the same when it comes to their relationship with pressure, temperature and volume. This means that regardless of what gas you inflate your tires with, be it the air we breathe, or any other inert gaseous element in a pure form like Nitrogen, they all act the same. Tire pressure is tire pressure, regardless of what gas is being used to inflate your tires.
When it comes to tire inflation and its effect on mileage, the type of inflation gas you use is less important than whether the gas (air) you use is DRY. If there is too much moisture in the supply lines used to fill your tires, you can add water with the air and this should be avoided. Too much moisture in your tires can cause corrosion and balance problems, so be sure to check that the air supply you are using is dry. Any shop that cares about their compressor equipment will have desiccant driers and water traps installed on the tank and lines to minimize any problems caused by moisture. Using Nitrogen to pressurize tires can help insure that the gas being used is dry, but it will in no way improve your mileage solely on the basis that the elemental gas Nitrogen is being used. Always remember, your mileage will vary more from improper inflation (usually being low), and your general driving habits, than from whether you use air or Nitrogen to inflate the tires. Not convinced?
Ask yourself this, “If using Nitrogen were so great for getting better mileage, why wouldn’t every trucking fleet on earth be using it?” The answer is because they already are. They use dry compressed air, and they know that over 78% of the air we breathe is the same Nitrogen these shops want to charge $30(+) for, just to inflate four car tires.
Don’t be caught up by the hype. If someone told you for $200 they would fill your tires with Helium to help make your car lighter, would you buy it? To some unquantifiable degree, using Nitrogen (or any other dry gas) could help reduce oxidation, but if the air being used to inflate your tires is dry, it will work just as well for everyday use. Since there are relatively few places along the road that have Nitrogen available for tire inflation, what do you do if your tire needs more pressure and all that’s available is an air hose at a gas station? You use the compressed air that’s available and you have just contaminated your $30 Nitrogen fill. Will this mean your non-guaranteed mileage increase from using Nitrogen would be spoiled? Don’t fret. For the world of casual drivers in the family car, who don’t ride on Z-rated racing tires, using dry compressed air will work just fine.
The factory owner’s manual that came with your vehicle does not tell you to use Nitrogen to inflate your tires, because they know it is not practical. If manufacturers could prove an increase in mileage for their car’s EPA mileage rating by using Nitrogen in the tires, trust me, they would be doing it.
You will find celebrity “car guy” testimonials on the Internet for using Nitrogen in your tires, but these folks can afford this sort of thing for their exotic collector car tires. Through their paid testimonials, they have a vested interest in the shops and equipment manufacturers that push the use of Nitrogen in tires for general use. They claim you might see a 4% to 10% increase in your mileage by using Nitrogen, but they won’t guarantee it. Save your money, and see to it that your tires are running on the correct air pressures. The same 4% to 10% may show up by doing this (but no one can guarantee that, either).
These shops often advertise that Nitrogen is what professional racers (and even Air Force One), uses in their tires to maximize performance. I ask you “Are you driving a racing team car worth hundreds of thousands of dollars that uses specialty tires?” When was the last time your daily-use vehicle ran 200+ MPH rated tires for racing at Daytona, or Indy, or the NHRA Winter Nationals?
Okay, there are some who simply want the best for their pride-and-joy set of wheels, and I can respect that. It gives you something to talk about, and it’s an exotic sounding option. Money is no object, right? For most of us however, the money would be far better spent filling the gas tank with $30 worth of fuel, then checking your tires for the recommended air pressure.
Anyone claiming they have improved their mileage by merely using Nitrogen should see the same mileage improvement from correctly inflating all of their tires with the same air that we breathe. Anything else is a waste of your money, and you will never recover the miles you would get from buying another tank of gas, compared to what you might save on the difference between using air versus Nitrogen.
Questionable tire inflation services aside, if you would like to see a tire pressure monitoring system on your next new car, write to the manufacturer, or ask your dealer if the option is available? If it is not, ask them, “Why not?” There are after-market pressure monitoring systems available, but this feature would be put to far better use as an option that the public can simply buy through the dealer or from the manufacturer.
Take my advice, and leave the use of Nitrogen to grocers for ripening their bananas. Don’t waste your hard-earned money on putting Nitrogen in your tires. Fill your gas tank with that money instead, and check your tires for proper, dry, “air” inflation.
More information on Tire Pressure Monitoring Systems (TPMS) can be found at
on this site.
More information on proper tire inflation can be found
here.
Palmer's Ponderings ArchivesMandating Bulbs That Use Mercury Is Not a Bright Idea (July 13, 2009)
Your Mileage Will Vary (July 7, 2009)
“The Answer, My Friend, is Blowin’ in the Wind . . ." (June 29, 2009)
“Build It, And They Will Come.” (Or Will They?) (June 22, 2009)
Tradeoffs And A Free Society (June 15, 2009)
Doug Palmer has had a life-long fascination with all things mechanical and electrical. Raised in Ames, Iowa, the home of Iowa State University of Science and Technology, he had the rare opportunity to go from kindergarten through college in the same community.
Upon completing a Bachelor of Science degree in Industrial Technology and Education from Iowa State in 1980, Doug moved to the northeast part of Iowa. While serving as the product development and production manager for a small manufacturing and metals fabrication facility, he met his wife, and in the mid 1980’s they moved to central Wisconsin where he joined the research and development team of a large manufacturing firm. After 14 years with this organization, and having authored several successful United States and Canadian patents for the company, he accepted an offer to join another firm to help it become more competitive.
After working in product development and engineering settings for nearly 20 years, Doug realized that most of the problems encountered in the business process (and society in general), are largely due to poor communication. With this in mind, he returned to the world of academia, and in 2005, he earned a Master of Arts degree in Communication, with an Organizational Communication emphasis from the University of Wisconsin, Stevens Point.
Today Doug operates Palmer Consulting, LLC, which is a product design and communication consultancy. As an independent, third party technical advisor, national and international organizations use Doug’s services to help improve their products, processes, and services.
He is a Senior Member of the Society of Manufacturing Engineers, is a member of Epsilon Pi Tau, the International Fraternity for the Advancement of Education in Technology, and is a member of the Everest Area Optimist Club Board of Directors.
In addition to his many years of formal technical training, Doug is an avid motoring enthusiast.