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Old 01-17-2014, 11:29 AM   #71
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CIP Cold Inflation Pressure or Inflation pressure when the tire has not been warmed above ambient by being in the sun or driven more than a couple miles for a few hours.
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Old 01-17-2014, 11:39 AM   #72
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Quote:
Originally Posted by hes4all View Post
Here's is a link to a study that is very interesting if you have time to read and are into numbers!http://www.nitrofill.com/documents/I...port101807.pdf
Another study below!Parker posts results of nitrogen tire inflation trialBy CCJ Staff Drexan

snip
I recall reviewing the report when it came out. I do have an observation that I was not able to get an answer for when I tried contacting the author.

Given that Rolling Resistance increases with a lowering of inflation pressure and an increase in RR results in lowering of Fuel Economy: How does using N2 which supposedly keeps tire pressure from rising as much as air during operation according to the data in the study, result in improved fuel economy?

Basically increased pressure improves MPG and lower pressure lowers MPG.
If using 95 - 97% N2 prevents the pressure rise normally observed when "air" 78% N2 is used as the inflation gas, how does the lower pressure and attendant increased tire deflection deliver improved MPG.

I would really like to get the answer to this question as this report is used to justify many of the claims made for selling N2.
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Old 01-17-2014, 11:54 AM   #73
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Sometimes, I find it is difficult for some people to let their common sense prevail when presented with TOO much information.

Keeping tires inflated properly only takes a few steps.

1. - Corner or Axle weigh your RV.

2. - Look at the tire manufacturer recommended inflation psi chart to determine psi for steer and drive tires based on the weight.

3. - Inflate each tire to the recommended psi + 5 lb's early in the AM before sunrise.

4. - Turn on your TPMS.

Enjoy your trip!

As Tireman9 has stated many times, this is not Rocket Science.

Dr4Film ----- Richard
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Old 01-17-2014, 02:14 PM   #74
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Nope, we ran them on everything but the steering axle. Caps come off for many reasons, but mostly I think from overheating from low pressure.
You are correct. Combine the low level of pressure maintenance for all types of vehicles be they passenger, LT, Heavy Truck, or RV low inflation results in higher temperature of the tire structure.
Increased temperature accelerates the break down at the molecular level of rubber which ultimately can cause the weakest component bonds to come apart.
When properly made and maintained retreads will deliver good tire life. In the aircraft industry that has very strict inflation maintenance guidelines multiple retreads of a carcass are sometimes seen.
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Old 01-17-2014, 02:24 PM   #75
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On The road My tire Pressure runs 105 in the front and 115 in the rear and does not waiver more than + or - 10 PSI based on Ambient temps changes.
I have yet to see a MH (not saying they don't exist) where the rear duals take more air than the front when adjusted for the actual weight unless the tire sizes are very different front to rear.
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Old 01-17-2014, 02:27 PM   #76
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I have yet to see a MH (not saying they don't exist) where the rear duals take more air than the front when adjusted for the actual weight unless the tire sizes are very different front to rear.
You've made this statement in the past and I gave you my weights and Michelin table and demonstrated to you that my rear duals took 90 and my steer tires took 80.
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Old 01-17-2014, 02:53 PM   #77
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You've made this statement in the past and I gave you my weights and Michelin table and demonstrated to you that my rear duals took 90 and my steer tires took 80.
X2 -

My steers are 105 psi Michelin's.

My drive axle tires are 110 psi Bridgestone's.

That includes the extra 5 psi in each one for bonus.

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Old 01-17-2014, 04:19 PM   #78
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I have yet to see a MH (not saying they don't exist) where the rear duals take more air than the front when adjusted for the actual weight unless the tire sizes are very different front to rear.
There you go 3 examples,

I weighed mine and used the tire Pressure Load chart to come up with those figures.

As I recall my motorhome is 8300 in the front and 15,600 in the rear.

Lots of overhang
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Old 02-19-2014, 04:32 PM   #79
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So we are getting ready to head south out of Ohio. DP has been sitting since November. Checked the air pressure and my inside duals are down to 50 psi. I normally run them at a 100. I was shocked they were that low. Now I'm wondering if it was the cold temperatures or if there is another problem. Two of the other tires we're at 90 and one at 70.
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Old 02-19-2014, 04:35 PM   #80
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So we are getting ready to head south out of Ohio. DP has been sitting since November. Checked the air pressure and my inside duals are down to 50 psi. I normally run them at a 100. I was shocked they were that low. Now I'm wondering if it was the cold temperatures or if there is another problem. Two of the other tires we're at 90 and one at 70.
May be another problem if only 2 were that low, Valve stems leaking?

Sidewall cracks?

Rusty rims?

Mine don't vary independently more than 1-2 lbs.

Ted.
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Old 02-19-2014, 05:59 PM   #81
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I'd be looking for a bigger problem. I can sit for months on end and the psi only varies a pound or two.

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Old 02-19-2014, 07:44 PM   #82
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Never had that problem. I guess I'd be looking for some nails in them. Could never loose that much with temperature variations.

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Old 02-20-2014, 10:58 AM   #83
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In general tire pressure is affected by temperature at about 1 to 2 psi per 10F change in Temperature. Increase Temperature will increase Pressure. So even though it might be 40 to 60 colder here in Ohio now than when you parked the RV that would only account for about 8 to 12 psi drop, which is what you are seeing in some of your tires.

If you had 100 psi when parked and if temperature accounts for only 10 psi drop the rest has leaked out.

Normal tire air loss runs about 1% to 2% per month so again this would only account for 8 to 12 psi loss (in addition to the loss due to temperature).

While punctures are a possibility I would be more suspect of your leaks of 5 psi per month being at the valve core, around the rubber O-Ring where the metal valve bolts to the rim or possibly rim corrosion if your rims are aluminum.

You can do some quick checks your self of the valve by spraying a dish soap and water solution.

Here is a post showing a slow valve core leak. A metal cap with a good O-ring might slow this leak further but air loss past or through the valve core is still possible.

This picture

shows the very small "froth" to the right of bubbles between the tire and rim. This tire developed a 3 psi per week pressure loss.

The other location you can inspect is around the area where the valve bolts into the rim. If you have pressed hard against the valve stem on the inner dual to get a reading you might have caused a ver slight loosening of the nut on the valve or distortion of the O-Ring. Also depending on the age of the O-ring it may have developed a leak as the rubber got hard due to time and temperature.

If all the above show nothing and a visual of the tires do not show a screw or nail then it is time to visit a tire shop for further inspection.
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Old 02-20-2014, 05:55 PM   #84
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I'll bet you have extensions on your inner duals. Cold temperatures cause dissimilar metals to contract differently, causing leaks.

I had that problem; very low pressure on the inners as soon as cold winter came it. I replaced them with Borg extended stems and no more leaks.
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