That 37% number way overstates the importance of the real difference. Here’s the quote from CR:
“The test started on September 20, 2006 and the final measurements were taken on September 20, 2007. The results show nitrogen does reduce pressure loss over time, but the reduction is only a 1.3 psi difference from air-filled tires. The average loss of air-filled tires was just 3.5 psi from the initial 30 pressure setting. Nitrogen-filled tires lost an average of 2.2 psi from the initial 30 psi setting. More important, all tires lost air pressure regardless of the inflation medium, so consumers should check their tires’ air pressure routinely. No evaluation was done to assess the aging claim.”
So after ONE YEAR the nitrogen loss was 1.3 psi less than the air loss. Totally meaningless in day to day normal car ownership. One should be adjusting pressures more than once a year, don’t you think?
I read that CR article when it was published and felt it was flawed, perhaps because the tires were stored in a warehouse and not in service. Tires generally lose 8 to 10 PSI after a year when in use.
That is not going to happen, most vehicles that come in for service have tires that are 5 to 15 PSI under proper pressure. Some customers will complain that the tire warning light is on while the display clearly shows that all four tires have just 25 PSI in them. Some drivers don’t know what pressure is normal.
Not only do I believe that to be true, I suspect most drivers don’t even know where to find out what pressure is correct for their car. I think most car owners don’t pay any attention to their cars at all beyond routine maintenance… if even that… until something goes wrong.
I don’t think however that the blasé attitude is unique to their cars. I think it also applies to their budgets, their houses, and even their health. We happen to be “car people”, but I believe we’re the exception rather than the rule. But I plead guilty to some of the other categories I mentioned.
Mrs. Vanderwert in Freshman Comp would be proud to think that a comma could make the difference between war and peace. Of course lawsuits have been won and lost from a simple comma. At any rate it has been well clarified what the guy should have said.
I once wanted to buy a Yotul Combi Fire 4 wood burning stove. I went to the library and looked past issues of the magazine and no mention of that stove. Period.
I asked the dealer about that, he said Consumer Reports was one of the biggest scams out there, In order for the stove to be tested, the company would have had to send 10 units to the lab with a check for $25,000. The company, that sold stoves all over Europe decided that having 15 stoves in their product line was not worth supplying this group of engineers with that much cash.
CR does not test anything for free.
In 10 years, if I am still alive, I am going to run an ad in the local papers, "If you need your car transported anywhere in America, I know how to drive a standard and an automatic. Since in 10 years most people will not have driver’s licenses, they might have owner’s licenses.
A missed placed period cost N A S A a rocket, due to miscalculation on the amount of pressure for a liquid fueled rocket.
For anyone who thinks that I meant to add more than the recommended pressure, here are a few extra commas just place them wherever you want to.
,
More important, I do not have the article in front of me, but I would guess, that should read More importantly.
It is not necessarily the lost of air, as much as the shape of the tire.
When a vehicle sits overnight in cold weather, the tires tend to sag and create flat spots.
Back in the 70’s before everyone was riding on Radial sidewall tires, there was a definite thump, thump, thump to all fiberglass sidewall tires, till the tire warmed up.
If you live in a warmer climate put air in your tires, I don’t care.
If your low pressure signal goes off, and you can just ignore it, fine drive like that forever. My new vehicle has a display that indicates what the pressure is in each tire. And I have had it for a year now and I have never seen the Low Tire Pressure warning light go on.
Some people say Merry Christmas, others say Happy Hanuka, or Happy Quanza,
I think everyone is missing the point, about what to put in your tires. If you fill them with helium, they will carry less weight, and last a lifetime, but not too much otherwise the car will float away.
Ever see those large earth moving tired trucks, their tires are filled with calcium chloride and water.
With such a small difference, I would like to know how many tires they tested and what the measured pressures were. If there is enough variability in the data, the 1.3 psi difference could be insignificant. CR might have taken that into account elsewhere in the article, it I don’t know for sure.
CR is not a scam. They buy all their samples, unlike other publications out there that get free samples from the manufacturer. All of their car tests are done using cars that they have purchased using anonymous car buyers so the manufacturers or dealers can’t specially prepare them, like they do for all the automotive magazines. CR is NOT perfect and they have certainly made their share of mistakes, but I feel like most of their guidance is pretty good.
The big problem people seem to have is when CR contradicts long held beliefs, mythology, or high powered marketing campaigns. It is very hard to let go of these things (like 3,000 mile oil changes or nitrogen filled tires). Most people choose to believe what they want to believe and rarely let facts or practical realities get in the way.
If you like nitrogen in your tires and you think there is a benefit then go ahead and put nitrogen in your tires. Personally I am with @bing on this one. Over 30 years of 78% nitrogen, 1% argon, and 21% oxygen has worked fine for me. I check tire pressures at least once a month and (on topic) my indirect TPMS works great in both my current vehicles. And just to stir the pot a little more, I change my oil every 7,500 miles.
Consumer Reports wanted to find out if nitrogen is worth the price, so we purchased a Nitrogen Inflation System and checked out how well the inflation held up over a one year period. We evaluated pairs of 31 tire models of H- and V-speed rated, all-season tires used in our tread wear test from 2006. We filled one tire per model with air and the other with nitrogen. The test was quite simple: fill and set the inflation pressure at room temperature to 30 psi (pounds per square inch); set the tire outdoors for one year; and then recheck the inflation pressure at room temperature after a one year period.
The tires were filled and deflated three times with nitrogen to purge the air out of the tire cavity. We also used an oxygen analyzer to be sure we had 95-percent nitrogen purity in the tire–the claimed purity limit of our nitrogen system, which generates nitrogen gas from ambient air.
The test started on September 20, 2006 and the final measurements were taken on September 20, 2007. The results show nitrogen does reduce pressure loss over time, but the reduction is only a 1.3 psi difference from air-filled tires. The average loss of air-filled tires was just 3.5 psi from the initial 30 pressure setting. Nitrogen-filled tires lost an average of 2.2 psi from the initial 30 psi setting. More important, all tires lost air pressure regardless of the inflation medium, so consumers should check their tires’ air pressure routinely. No evaluation was done to assess the aging claim.
Bottom line: Overall, consumers can use nitrogen and might enjoy the slight improvement in air retention provided, but it’s not a substitute for regular inflation checks.
My comments aren’t directed at what he SHOULD have said. They’re directed at what he SAID.
Twisting people’s words to change their meaning doesn’t make the one doing the twisting correct… generally only misleading. It is possible that the OP meant something other than what he wrote, but unless he himself tells me that I’m not gong to be so arrogant as to think I knew what was in his mind when he wrote the statement. I’ll take his statement as written.
Well, it answered part of your question, but didn’t answer the part needed to calculate the standard deviation.
And for those folks who don’t understand why that is important: Having the values can allow a statistical calculation (I think it is called Student’s T) where it can be determined the probability of 2 averages being different.
“Like most aircraft tires, the Space Shuttle tires are filled with Nitrogen because of its stability at different altitudes
and temperatures. Also, Nitrogen molecules are larger than Oxygen molecules, which means Nitrogen escapes less
easily from the tires, resulting in a more gradual loss of pressure over time. Nitrogen is also non-flammable which
prevents problems should a tire puncture upon landing.”
Yes, Students T is needed in this case since the sample size is less than 35. Comparing the two means using the standard deviation of both samples tells us the probability of the two means coming from the same sample.
