Save Big Bucks On Gasoline!!!!!

[caseydog]

I have been preaching the gospel of checking the air pressure in your tires for many years -- both for safety and fuel economy.

Here are some interesting facts about tire pressure and fuel economy...

The National Highway Traffic Safety Administration estimates one-in-four cars and one-in-three light trucks and SUVs has one or more tires under-inflated by 8 pounds per square inch (psi) or more.

The Carnegie Mellon University Sustainable Earth Club studied 81 random vehicles in a parking lot and found that 80 of the 81 had under-inflated tires. The average rate of under-inflation was 20% -- soft tires, indeed.

The EPA estimates that for every 1 psi of under-inflation, fuel economy drops by 0.4%. That's not much, but if the tires are under-inflated by 8 pounds, that's a 3.2% drop in fuel economy. About 1.2 billion gallons of fuel are wasted annually due to under-inflated tires, the NHTSA estimated in 2005.

Get a good tire gauge and use it. You don't have to spend a lot, but buying something better than the cheap pencil-style gauges is probably worth it.

Most cars have a chart showing what the manufacturer recommends for front and rear tire pressures. You may be surprised at the recommendations. The recommended pressure on my own car is higher than I would have expected, and is higher for the rear than for the front.

Under-inflated tires are also dangerous. They heat up fast, and get too hot. This can cause tire failure -- as in a sudden blowout.

So, save gas, money, and possibly your life by keeping your tires properly inflated.

CD

[Mark & Andrea Jones]

Yep. Unless your mechanic is better than ours is, whenever you have an oil change and it also involves checking fluids and pressures, then you will want to RE-CHECK your pressures after you get the car/truck back. I have found that the mechanic only looks at the PSI on the side of the tires - they don't look at the recommended pressures for the specific vehicle which are posted on the B column in my Forester.

However, this also begs the question - which one do you follow? The tire manufacturer or the car manufacturer? Personally, I go with the car manufacturer.

Andrea.

[asianflava]

Funny you should mention this, I was just talking about it yesterday. When I was setting my car up for auto-X the parts manager at the Honda dealership sent me to a shop to get the car aligned. My Honda dealership campaigned a car in the old Firestone Firehawk series. Local hotshoe Randy Probt was their driver.

The guy at the shop showed me that the recommended pressure on the tire and the recommended pressure on the car were different. The pressure on the car was typically lower because it gives a slightly softer ride. He said to go with the pressure on the tire because it gives better fuel economy and better handling.

[Joseph]

One of the cool things about getting my tires from Costco is that they fill them with nitrogen. Apparently the molecule is larger and is less prone to leaking through the tire.

Better living through modern science!

Joseph

[madjack]

...I always go with the pressure the tire manufacturer gives...this the pressure the tire is best suited for...as Rocky stated, the car manufactures recommendations is for ride...can this make a difference...ask the guys who where having the roll overs in Fords, a few years ago!!!!!!!!!!!!!
madjack

[Leon]

The pressure on the tire is the MAX for the rated load of the tire. Most times the tire is not near the rated load and doesn't need as much pressure. The data on the car takes that into consideration and is the optimum pressure for that tire on that car. Overinflating can offer less rolling resistance but at the cost of less traction in stopping situations. Radials aren't as sensitive to this as bias ply tires were, but the car manufacturer's ratings should be followed.
A good example is a T bucket we built a few years ago, the tires on the back were rated at almost 2000 pound capacity at 35 PSI, but at that inflationit looked like a doughnut with a very small contact patch. We ended up running 20 PSI to get the best contact patch with the 700 pounds that was on that tire. The tire manufacturers won't officially admit to any pressures other than the MAX on the side of the tire for legal reasons, but the rep I spoke to said thet most tires don't need the MAX pressures listed because the tires aren't being loaded to the MAX.

[Mark & Andrea Jones]

The guy at the shop showed me that the recommended pressure on the tire and the recommended pressure on the car were different. The pressure on the car was typically lower because it gives a slightly softer ride. He said to go with the pressure on the tire because it gives better fuel economy and better handling.

The interesting thing that I have noticed is that we get better gas mileage (2 - 5 mpg) when the tires are inflated according to the vehicle manufacturer rather than the tire manufacturer. It also handles and hauls the TD better and gets better MPG hauling, too.

Go figure. I guess everybody's got a different answer.

Andrea.

[Steve_Cox]

One of the cool things about getting my tires from Costco is that they fill them with nitrogen. Apparently the molecule is larger and is less prone to leaking through the tire.

Better living through modern science!

Joseph

I use a gas mix in my tires that is found in the troposphere, it generally consists of the following proportions of gases: 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, 0.03 percent carbon dioxide, and the remaining 0.07 percent is a mixture of hydrogen, water, ozone, neon, helium, krypton, xenon, and other trace components.

[Mary K]

Good one Steve.

CD, you sure do like to start posts about controversial issues.

Mk

[Mary K]

I'm with Steve...lets lighten things up....

I like inert nitrogen in my tires. It's environmentally stinky BUT friendly.

Mk

[caseydog]

My experience with all the press cars I get is that some types of cars and manufacturers go with a lower pressure on their recommendation stickers, while others go higher. Volvo recommends some pretty high pressures. While, at the other extreme, some of the truck platform SUVs go with less pressure, to soften the ride with their "truck" suspensions.

I tend to go for a higher pressure, and will experiment to find the best pressure, which is usually pretty close to the car manufacturers levels.

The tire manufacturer really can't predict the size and weight of the cars that their tires will end up on.

On my 2,400 pound Miata, 28 PSI was plenty of pressure, but on my 4,200 pound Audi, I run about 36 PSI.

CD

[duke]

PHILADELPHIA (Reuters) - As U.S. gasoline prices hit records on almost a daily basis, an increasing number of motorists are following a radical driving technique designed to eke out every last mile from a tank of fuel.

Known as 'hypermiling,' the method can double gas mileage, even in gas-guzzling vehicles that would normally get less than 20 mpg.

Promoted on a growing number of Web sites, hypermiling includes pumping up tires to the maximum rating on their sidewalls, which may be higher than levels recommended in car manuals; using engine oil of a low viscosity, and the controversial practice of drafting behind other vehicles on the highway to reduce aerodynamic drag -- a practice begun a few years ago by truck drivers.

The price of gasoline -- which hit a record of nearly $3.61 per gallon on Tuesday, according to travel club AAA -- has rapidly emerged as the public's biggest economic concern.

Gas prices are a "serious problem," ahead of jobs, and healthcare, according to a poll released on Tuesday by the Kaiser Family Foundation.

The "advanced" techniques of hypermiling are in addition to well-known approaches including keeping speed down, accelerating gently, avoiding excessive idling and removing cargo racks to also cut down on aerodynamic drag.

Adherence to hypermiling and other disciplines are designed to boost mileage well in excess of the U.S. Environmental Protection Administration's official ratings, which apply to each car model.

COSTS SAVED

Wayne Gerdes, a former nuclear plant operator from Wadsworth, Illinois, and the originator of hypermiling, said he gets 40-70 mpg out of his Ford Ranger pickup truck, about doubling its official fuel consumption of 25 mpg.

Gerdes, 47, estimates that hypermiling has saved him $15,000 in fuel since he began the technique after the attacks of September 11, events that convinced him that U.S. national security was being undermined by its dependence on oil from the Middle East, and motivated him to reduce his own fuel consumption.

"If every vehicle in the U.S. got 45 miles per gallon, we would not import any oil," he said.

Deron Lovaas, vehicles campaign director at environmental group the Natural Resources Defense Council, said most hypermiling techniques are "sensible recommendations" that could drive down demand and even prices if widely adopted.

"We should be looking under every rock for potential energy savings," he said.

He said he could not recommend drafting behind fast-moving trucks because it could potentially lead to highway accidents.

Hypermiling can even make fuel-sipping gas-electric hybrid cars more efficient. Chuck Thomas, 50, a computer programmer from Lewisville, Texas, said he has been getting 71 mpg from his Honda Insight, a hybrid whose EPA rating is 58 mpg, in the two years since he has been hypermiling.

Among Thomas' techniques is "pulse and glide" in which he accelerates and then coasts with the engine off until around 15 mph when he kicks the engine back on and accelerates again. "It's the automotive equivalent of skateboarding," he said.

(Editing by Timothy Gardner and Philip Barbara)

[caseydog]

40-70 mpg from a Ranger pickup sounds pretty hard to believe. And, yes, drafting is not a good idea on public rods.

However, over-inflating tires, to a certain degree, can eek out some additional mpgs. It will make for a rough ride, and may wear the tires out prematurely, but it is not really dangerous, unless you go way too far.

Realistically, just keeping the tires up to reasonable pressures will be a big improvement over the norm, where most cars on the road are not up to proper inflation.

Just bothering to check your tire pressure on a regular basis is enough to make a significant difference.

CD

[pete.wilson]

Hey

Caseydog makes a good suggestion about tire inflation. One point I would make also is the suggestion of NOT using those flashy little aluminum valve caps on your wheels. My were only about two years old when I noticed a tire that looked low, but when I tried to check it, I couldn't get the cap off. Three out of four valve stems were badly corroded and had to be replaced at the tire shop. I will only use plastic caps from now on.

Pete Wilson

P.S. As for hypermiling: The controversial practice of drafting behind other vehicles on the highway to reduce aerodynamic drag -- a practice begun a few years ago by truck drivers. That's BS, southern rednecks have used it for years..........NASCAR BABY!!!!!!
If done by Northerners, it's called Tailgating and you could get shot!!!!!!

[planovet]

I keep my tires at about 35 psi. With my tire pressure monitoring system I don't have to leave the driver's seat to check the pressures. It's interesting to watch the pressures go up and down with tire temperature. CD is right, tire pressure is very important, in more ways than MPG.