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07-09-2007, 08:30 PM
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#1
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Guest
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Some thoughts on tire failure...
I just got back from a 7,000 mile trip. I am happy to say the TM held up well, although I've got a list of things to get fixed in the TM (leaking water inlet hose, piece of upper wall molding falling off, countertop chipped, rock guard doesn't close right, etc). But overall I'm very happy, and I expect all of these things to be fixed when I take the TM back to my dealer at the end of the season (I'll report back though!).
As I was driving, I thought of a few ways we might be contributing to tire failure.
1. Full tanks. My 40 gallon freshwater tank plus 6 gallon hot water tank add about 368 pounds, or over half the total cargo capacity to the street side wheels. That's probably pushing things.
2. High speed. The faster you go, the more a given stretch of tire has to flex.
3. Overloading with too much stuff!
4. Weight distribution - say 600 pounds of tongue weight, you are sending 200 of that back to the wheels. That cuts significantly into your payload capacity (more than 200 pounds of payload quite possibly, see next point).
5. Badly distributed weight. If you put weight in the back, you lower the tongue weight (the trailer pivots on the wheels). So, if I add 10 pounds of weight in the back, and that lowers the tongue weight by 5 pounds, I've added 15 pounds (my new 10 plus the 5 the tongue was supporting) to my tires. The further back your weight, the more weight you put on the tires, but it's *ALWAYS* more then the actual cargo weight unless you put your weight in front of the tires!
6. Accessories not included in the dry weight
Are there other things that we can control that will give us longer tire life?
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07-10-2007, 03:00 PM
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#2
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Guest
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Two thoughts on tire failures...
Has anyone used nitrogen in tires instead of air? No change in pressure with temp. or altitude. I have it in my TV (2008 F250). By maintaining constant pressure there should be less chance of failure dueto over/under inflation. Also, it has been recommended to me to have a laser alignment of axle vs frame to reduce side loads. In answer to obvious question - I haven't checked on availability of nitro other than thru truck dealer.
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07-10-2007, 04:00 PM
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#3
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Site Sponsor
Join Date: May 2002
Location: Downsville, Louisiana
Posts: 1,069
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Quote:
Originally Posted by Fdxflyer
Has anyone used nitrogen in tires instead of air? No change in pressure with temp. or altitude. I have it in my TV (2008 F250). By maintaining constant pressure there should be less chance of failure dueto over/under inflation.
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Do a search on nitrogen for additional info.
__________________
Mike Laupp
2013 Jayco Eagle Premier 351RLTS 5er - Honda 2000i x2 w ext. run tank
2017 F350 King Ranch ultimate CCLB SRW 6.7L V8 TD Fx4 BakFlip F1 & BakBox
TM History: '97 2720, '02 2720SL, '03 2720SL, '04 3326K. 2001 - 2012 yrs owned.
1990 Isuzu Trooper II 283 V6
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07-10-2007, 04:38 PM
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#4
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Site Team
Join Date: Feb 2003
Location: The mountains of Scottsdale, AZ, and the beaches of Maine
Posts: 10,088
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Quote:
Originally Posted by Fdxflyer
...nitrogen instead of air? No change in pressure with temp. or altitude.
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Excuse me? Someone has been jerking your chain (or your wallet) pretty badly. I hate to be a bummer, but you seriously need to do some research - and then change tire mechanics.
Bill
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07-10-2007, 05:05 PM
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#5
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Site Sponsor
Join Date: Oct 2004
Location: Southeast of Houston, Texas
Posts: 1,089
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Why wouldn't an N2 inflated tire change gauge reading with altitude? It's the outside pressure that changes when elevation changes, not the tire pressure.
Gauge pressure = pressure in vessel - ambient pressure. A tire inflated to 50 psi at sea level has 64.7 psi in absolute terms. If you go up to 14000 feet the ambient pressure will be 0.587 * 14.7 = 8.6 psi. Your gauge would then read about 56 psi. Nothing changed about the gas in the tire.
I'd guess the stress/strain on the tire carcass is a function of the differential pressure, so it makes sense to use gauge pressure where you are to inflate the tire.
Also, N2 definitely does change pressure with temperature changes. Pressure = gas constant * mass * temperature / volume to a first approximation for any gas at reasonable pressures. The constant may change but the proportion is there. Also, remember air is mostly N2 in the first place.
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07-10-2007, 05:26 PM
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#6
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Guest
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+ air is free and N2 isn't. About the only plus I can think of is that N2 probably is less of a corrosive to the inside of the tire. I think your tire guy sold you a bill of goods.
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07-10-2007, 05:53 PM
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#7
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Guest
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According to what I have read N2 has a different molecular structure than O2 and diffuses at a different rate which helps in maintaining pressure,i.e. it doesn't leak out as fast. Water vapor present in your compressor air and far less so in N2 also contributes to corrosion and variants in pressure. Bottom line, regardless of the specific mechanics, if N2 was no better why would race car tires, airplane tires and numerous other high performance vehicles have N2 in their tires? As far as cost goes, anything I can do to reduce the risk of a blowout (a problem many have written about but nobody really seems to know why or have a solution for) I'll spend $10 a tire for N2 for the life of the tire. Seems like cheap added insurance to me.
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07-10-2007, 06:16 PM
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#8
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Guest
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We have several sales reps trying to sell us a nitrogen system at my shop. Tires running cooler and losing pressure slower, are always their stressed selling points to me. I took the following from one of the sales brochures we have for a Branick Nitrogen system. Maybe this will help:
Nitrogen Inflation Program
BRANICK
Benefits of Nitrogen Filled Tires:
Maintains Air Pressure Longer
Tires Run Cooler
Customers Return To Maintain Air Pressure/Tire Dealer Checks Vehicle for Maintenance
Even tires properly inflated lose pressure because oxygen migrates through the tire innerliner. Nitrogen migrates 3 to 4 times slower than oxygen preserving the inflation pressure for up to three times longer. Nitrogen contains no moisture. This, combined with the elimination of oxygen, reduces rust and oxidation of the wheel and innerliner. Tires also run cooler since nitrogen retains less heat than oxygen. The Branick Nitrogen Tire Inflation System is a free-standing nitrogen generation system using an internal membrane to separate nitrogen from the air provided from your air compressor. Tires may be inflated directly from the station or nitrogen can be stored in a backup tank for additional capacity.
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07-10-2007, 07:19 PM
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#9
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Guest
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Nitrogen has a greater thermal conductivity than air, so if the heated nitrogen can get to a cool surface (the wheel rim?) the heat can be carried off more quickly resulting in a lower temperature. How much lower? I can't answer that.
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07-11-2007, 02:34 PM
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#10
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Guest
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I guess I stirred the pot enough with the nitrogen. Any thoughts out there about the axle/frame alignment? I have taken it for granted they would be aligned but if they aren't it would seem to cause a lot of sidewall stress which it sounds like is what is failing in the reported failures. But then, if they were not aligned it would also seem that the TM would not track properly. Just thoughts readers... I'm no expert and it seems there is a problem and nobody appears to have a real answer so I am just bouncing ideas.
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