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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: Kristinsgrandpa on July 26, 2007, 07:32:41 AM

Title: More tire info......maybe.
Post by: Kristinsgrandpa on July 26, 2007, 07:32:41 AM
While reading the thread from Fleetowners I followed a link to a trucking website and found this tidbit:


Nitrogen inflation improves tread life, fuel economy: Study
07/09/2007 
VANCOUVER -- Recent research conducted and funded by nitrogen tire inflation proponent and equipment supplier, Vancouver-based DREXAN, showed improvement in both tire tread life and vehicle fuel economy in a long-haul trucking fleet.
Drexan's president, Konrad Mech researched and authored the study, and presented the results at the 23rd annual Clemson University Tire Industry Conference in South Carolina in March 2007.

 
 
Nitrogen filled tires maintain proper
inflation pressure for longer periods.
When used for tire inflation, nitrogen is said to all but eliminate pressure loss because the gas won't penetrate the tire casing the way ordinary air will. As a result, tires maintain proper inflation pressure for longer periods.
Harris Transport of Winnipeg paid $8,500 to convert 65 percent of its fleet to Nitrogen. The study comprised over 177 million tread-km for 1,988 tire positions. In the tires inflated with air, a control group of 452 tire positions showed an average of 5.38 mpg, and an average tire life of 26,623 km per 32nd of tread wear. A group of 836 nitrogen-filled tires, the study says, produced 5.56 mpg, with 49,748 km per 32nd of tread wear.

That's a fuel economy increase of 2/10ths of a mile per gallon, Mech notes, and a tread life increase of 86 percent. During the trial, the additional fuel efficiency translated to a savings of over 500,000 liters of fuel, or roughly $425,000 in fuel cost savings.

"Drexan completed the long-haul trucking trial to determine the benefits of Nitrogen tire inflation, and the results exceeded our expectations," says Mech. "Moreover, fuel efficiency of the nitrogen inflated equipment increased by 3.3 percent even though the tire pressure of the air inflated tires was aggressively maintained. We did not expect this, so it is very good news."

The results were obtained by measuring tread wear on an air inflated control group comprising 35 percent of the trial fleet. The results were statistically analyzed by a PhD statistician and were found to be highly significant. The final report with statistical data was submitted to Transport Canada for their in-house technical review on March 30th.

For a copy of the study, call Drexan's Konrad Mech at 800-663-6873, or 604-431-6400, ex 2104.

 
But at what cost to the busnut, if available at truckstops free gratis then OK, but if you have to buy its expen$ive.

Thats almost .2 MPG.

Ed
Title: Re: More tire info......maybe.
Post by: RJ on July 26, 2007, 07:36:01 AM
Many of the Costco Tire Departments nationwide have been filling their customer's tires with nitrogen for a couple of years now.  Same reasons as quoted in the study.

Easy to spot a Costco tire customer - tire valve caps are green.

FWIW& HTH. . .

 ;)
Title: Re: More tire info......maybe.
Post by: Stan on July 26, 2007, 10:41:44 AM
I don't understand the short term loss of air through the tire. Last year I donated a car to a museum that had been parked since 1964. I am guessing that the tires had about 30 PSI when parked and three tires were still above 20 PSI (one tire at 10 PSI) 42 years later. Since modern tires have softer sidewalls, does the flexing of the tire massage the air through the rubber?
Title: Re: More tire info......maybe.
Post by: niles500 on July 26, 2007, 12:27:41 PM
"If you check your tires regularly"

Air = 78% Nitrogen

If you leak the other 22% then refill with the same AIR containing 78% nitrogen and 22% of that leaked out then after 1 refill you should be at 95% Nitrogen and after a second top off almost 99% Nitrogen - It's just in the math -
Title: Re: More tire info......maybe.
Post by: kyle4501 on July 26, 2007, 01:08:35 PM
I'm with Niles500 on this one.

I don't know much, but it smells a little odd. . . . AND this research was conducted and funded by nitrogen tire inflation proponent and equipment supplier. Just how unbiased do you think they will be?
Curb side tires wear faster than road side on my trailer, is that because of what's inside the tire? I think it has more to do with the edge of the road having more debris on it.

Several questions occurred to me concerning this test.
Were the tires loaded the same?
Were the useage temps the same?
Were the roads the same?
Were the speeds the same?
Were the trips the same?

What is the PhD's background? How much was he paid for his favorable opinion?

With so many unanswered questions, it's tough for me to feel it is anything other than marketing hype.

Putting pure nitrogen in the tire won't hurt anything & lets Costco have something that separates them from the other tire stores & that may work for them.

I won't bother with nitrogen until the tire manufacturers require it for warranty.

YMMV
Title: Re: More tire info......maybe.
Post by: tekebird on July 26, 2007, 01:10:26 PM
It is true, Nitrogen has been used for years now in Auto racing.

to be properly inflated they have to be inflated with no static load!!!!!!!!!!!!!!!!!!
Title: Re: More tire info......maybe.
Post by: bassfid on July 26, 2007, 02:16:48 PM
My undertanding of the Nitrogen use in tires (especially racing) was to eliminate moisture which can cause an increase in pressure at high temperatures encountered in racing.  Even 1/2 pound can change the handling characteristics in a racing tire.  I doubt that any of this would be an issue in your bus or car tires.
Title: Re: More tire info......maybe.
Post by: gus on July 26, 2007, 02:26:48 PM
This old wive's tale surfaces on these forums every few months. It is an attempt by the nitrogen manufacturers to increase sales dramatically.

So far it has not worked, another snake oil product.

It is great stuff but not worth the expense. After a few people are maimed by the nitrogen high pressure systems it will fade away.
Title: Re: More tire info......maybe.
Post by: kyle4501 on July 26, 2007, 02:54:50 PM
Yep, the dryness of nitrogen is a real plus, especially if you're using a tire balance powder that clumps when wet.

But if the air system has a proper air drier installed, then air will be just as dry.

Title: Re: More tire info......maybe.
Post by: tekebird on July 26, 2007, 02:56:29 PM
Not snake oil but likely not worth the expense.

benefits.

Nitrogen does not leach out of the tire thus preasure remains more constant over time
Nitrogen does not change preasure as much once heated: Tires stay cooler
Tires stay cooler:  Better wear better mileage.

Drawbacks:  Cost: 5.00 per tire(car) in my neck of the woods
Title: Re: More tire info......maybe.
Post by: TomC on July 26, 2007, 04:17:11 PM
I know at least the Costco I go to for my car tires uses Nitrogen as standard.  My tire stem caps were replaced with green ones to indicate Nitrogen.  Good Luck, TomC
Title: Re: More tire info......maybe.
Post by: Tony LEE on July 26, 2007, 08:59:24 PM
Clever marketing. Fill the new tyres free with Nitrogen. convince the customer of all the benefits, and then charge for top-ups forever.
Title: Re: More tire info......maybe.
Post by: TomC on July 26, 2007, 09:30:53 PM
Every 5,000 miles you take your car to Costco and they rotate the tires, recheck them for balance and top off the pressure for FREE!  That's why I buy from Costco.  Good Luck, TomC
Title: Re: More tire info......maybe.
Post by: DrivingMissLazy on July 27, 2007, 06:18:56 AM
I bet when you need new tires you will buy them from Costco. I know I would. Really smart marketing on their part in my opinion.
Richard

Every 5,000 miles you take your car to Costco and they rotate the tires, recheck them for balance and top off the pressure for FREE!  That's why I buy from Costco.  Good Luck, TomC
Title: Re: More tire info......maybe.
Post by: Prather on July 27, 2007, 06:54:24 AM
Just thinking, aren't  tire pressure recomendations from the tire manufacturer based on air with a expectation that pressure will increase as the tires heat up?  If this is true and nitrogen doesn't expand as fast as air would not the tires be underinflated for a long haul?

Prather
Title: Re: More tire info......maybe.
Post by: niles500 on July 27, 2007, 09:20:49 AM
I agree Prather - "hot inflation" pressure would be dependent on multiple variables including ambient temp, road surface temp, % of water vapor in tire, speed of vehicle, and the amount of force or friction being applied to the tire. I've never done the test but I have heard up to 10% pressure increase is normal for summer at highway speeds.

Consider this ;

Your leaving Fairbanks, AK in the winter and heading to Brownsville, TX - Before you leave you fill your tires per 'cold inflation' instructions to 100 psi (air or nitrogen - take your pick) - you then drive to Brownsville - what do you suppose your 'cold inflation' is now? - Now think about the return trip - Not to mention that the air gets thinner as your longitude or elevation goes higher - that's why I just keep my tire at the highest psi for the load and check them often - I don't like it when safety equipment is marketed as 'maintenance free' because it really isn't - there are many things other than leaking oxygen that will cause your tires to underinflate and only the constant physical inspection and pressure testing of each tire will ensure safe operation - FWIW
Title: Re: More tire info......maybe.
Post by: niles500 on July 27, 2007, 10:10:53 AM
In addition - for the scientific types - the relative molecular mass (0 degrees centigrade/1 atmosphere) of Nitrogen= 28 and Oxygen= 32 - and a Diffusion coefficient (mm sq.) of Nitrogen= 17.5 and Oxygen= 17.5

At different temps and/or pressures the diffusion rates will vary -