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Old 10-20-2013, 02:59 PM   #31
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Mikegjax, the tire placard on the trailer is useless if the tires have been upgraded to a higher load range. Same goes for the truck placard. Tire pressure will increase more than 5# or 6# in a very short time on the road. I have experienced pressure increases of 10#, which sounds the TST TPMS alarm. Did I bleed them off? No, we just took a coffee/pie break and let them cool off for about 30-45 min. Had we been in a hurry and not wanted to take the break, I would have bled them off and re-inflated the next morning. The temperature alarm is factory set at 157° as TST states that most tire failures occur between 180° & 200°.
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Old 10-20-2013, 04:54 PM   #32
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Would inflating with nitrogen make a difference cold vs hot tires.
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Old 10-20-2013, 04:58 PM   #33
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Would inflating with nitrogen make a difference cold vs hot tires.
Have heard that the tires run cooler, but have no experience with the Nitrogen filled tires. Normal air is approx. 78% Nitrogen. Don't know if the additional 22% would help.
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Old 10-20-2013, 07:44 PM   #34
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We always used nitrogen for aircraft tires for several reasons. Pull the following info. from a web site and it might answer some questions.

First is that nitrogen is less likely to migrate through tire rubber than is oxygen, which means that your tire pressures will remain more stable over the long term. Racers figured out pretty quickly that tires filled with nitrogen rather than air also exhibit less pressure change with temperature swings. That means more consistent inflation pressures during a race as the tires heat up. And when you're tweaking a race car's handling with half-psi changes, that's important.

Passenger cars can also benefit from the more stable pressures. But there's more: Humidity (water) is a Bad Thing to have inside a tire. Water, present as a vapor or even as a liquid in a tire, causes more of a pressure change with temperature swings than dry air does. It also promotes corrosion of the steel or aluminum rim.

How is water relevant to a nitrogen discussion? Any system that delivers pure nitrogen is also going to deliver dry nitrogen. Filling tires with nitrogen involves filling and purging several times in succession, serially diluting the concentration of oxygen in the tire. This will also remove any water.

It's certainly simple, although time-consuming, for a tire technician to fill and bleed tires. But most shops use a machine that not only generates almost pure nitrogen by straining the oxygen out of shop-compressed air, but will also automatically go through several purge cycles unattended. Some shops have been charging as much as $30 per tire for this service. I think that's too much. If you're buying a new tire, it should be far less. Still, the nitrogen generator, filling system and technician's time aren't free—the dealer is entitled to some return for that.

So, to answer your specific questions: With nitrogen, your tire pressures will remain more constant, saving you a small amount in fuel and tire-maintenance costs. There will be less moisture inside your tires, meaning less corrosion on your wheels. You will not be able to feel any difference in the ride or handling or braking, unless your tire pressures were seriously out of spec and changing to nitrogen brought them back to the proper numbers.

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Old 10-20-2013, 09:48 PM   #35
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I am a new owner of a 24S and I can see that suspension upgrades are needed right out of the box. I have ordered the Hellwig sway bar and will make a decision on shocks after I install it. Because of this I have come to the conclusion that the sprinter chassis was designed for a lighter cargo van and is maxed out with the motorhome weight. So I am now pondering tire pressure and wondering if it should be increased also. I would appreciate any thoughts you have on this, and would like to know if anyone agrees and has increased tire pressure, and what were your results in handling and increased MPG.
It would help if you could provide some numbers. Your placard will have data for GAWR and GVW. You should also have a label showing the capacity of additional load for your vehicle.
Tire size and Load Range will help us provide answers on the tires and your actual load as measured on a certified scale will help confirm some important numbers.
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Old 10-20-2013, 09:52 PM   #36
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As long as he re-inflates them to the right pressure when cold, it shouldn't hurt a thing. Just more work.
Absolutely NOT. You should never let air out of your hot tire. Doing so and then reinflating that evening is NOT a good idea. Also a lot of un-necessary work. Tires will normally run 10 to 25 psi above the cold infla depending on a number of variables.
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Old 10-20-2013, 09:57 PM   #37
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I guess we'll just agree to disagree. Perhaps Tireman9 can educate one of us.

Tires are designed and tested at a "caped" air pressure. That means the infl is set when the tire is at ambient and not adjusted during the durability or high speed regulatory tests. Tires will get hot and the pressure will increase. This is what is supposed to happen.
If you lower the inflation (when hot) the tire will flex more so it will generate more internal heat and more internal structural damage will occur. This will cut tire life considerably. You will not find a tire engineer ever suggesting bleeding hot air for regular road service.
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Old 10-20-2013, 09:58 PM   #38
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Absolutely NOT. You should never let air out of your hot tire. Doing so and then reinflating that evening is NOT a good idea. Also a lot of un-necessary work. Tires will normally run 10 to 25 psi above the cold infla depending on a number of variables.
Please explain the harm. Extra work I fully understand. If my alarm goes off at 10# excess pressure I just stop and let them cool. TST TPMS recommends 15% over cold pressure as the alarm setting. In my case that's 10#.
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Old 10-20-2013, 10:00 PM   #39
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Just means that you need to add air when the tire cools. Makes no sense to me to deflate a hot tire, but if that's what the man does, it can't do any harm as long as he re-inflates when the tires cool. Will say this, over inflating hot tires will definitely stretch them. We used to over inflate tires on our race car and set them in the sun to stretch them. We could get the circumference to change by as much as 3"-4" over stock, which is how we got "tire stagger".
Bet those tires were bias ply not steel belted radials.

Race car drivers do a lot of things that should not be done for regular highway use.
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Old 10-20-2013, 10:04 PM   #40
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So you're saying if I set preferred cold pressure and pressure builds to 85psi on a hot day (exceeding stated sidewall pressure) I should run them at that pressure? I disagree... But to each his own. I've blown tires in the past running them at excessive pressure when hot.

If you have "blown" tires that means they were probably run low flex failures.

Tires are designed to handle three to five times the pressure on the sidewall. If you read the words you will see the cold pressure does not say "max pressure" but "Max Load @ xyz pressure"
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