Truck tire pressure

[Mace Canute]

Nitrogen is also used in aviation to eliminate oxygen in the tires. From AERO : Wheel and Tire Servicing

Inflating wheel/tire assemblies only with nitrogen.
Tires must be initially inflated only with nitrogen. However, air can be used to top off a low-pressure tire if the airplane is in a location where nitrogen is not readily available, provided that the oxygen content does not exceed 5 percent by volume. Optional procedures for ensuring that the oxygen content in the tire will not exceed 5 percent are typically found in chapter 12 of the AMM. These procedures include a table that lists the maximum refill pressure versus the initial tire inflation pressure. The sum of all air pressures added to a given tire cannot exceed the pressure shown in the table for the corresponding initial inflation pressure.

Summary
In the past 20 years, a few accidents have occurred during tire servicing in which the wheel exploded because of overpressurization or high oxygen content, causing serious injury or death to service personnel or damage to equipment. Strict adherence to established procedures in the AMM and CMM will help ensure the safety of maintenance personnel during tire servicing. In addition, it is essential that tire-servicing equipment is equipped with a regulator to prevent tires from being subjected to excessive pressures that can result in an explosion.
Brian Chelius
Principal Engineer
707/727/737/757
Service Engineering
Boeing Commercial
Airplanes

 

[arsenix2001]

No, you're not trying to argue, much less debate. You're merely repeating what you've heard as if it were fact. Since you're TheTrailerGuy I'm assuming a lot of your experience pertains to trailers. All my life I've seen U-Haul rental trailers with big signs on the fenders like "Inflate tires to 60 psi" or something like that. That's if you're hauling the trailer empty or loaded to maximum. The reason is that U-Haul doesn't want to see a tire fail from underinflation. They don't really care if the trailer bounces and rattles when empty or if the tires wear out the centre of the tread from overinflation because they'll probably die of old age before that.

However, this thread is about truck tires. "Trucks" can be a variety of vehicles. If you drive one of those yuppie Porsche Cayenne SUVs, don't want to be inflating your tires to the maximum sidewall number because some redneck in a Ford pickup will be able to outdrive you as you go skittering off into the weeds on a twisty road. Generally, trucks used for personal transportation carrying just the driver should have their tires inflated to the door jamb pressures for best comfort and roadholding. 18-wheelers, however, would probably run the maximum sidewall pressure just to be safe. If they're never carrying a load, they should be in a different line of work.

+1 :thumbsup:

 

[Reg]

and the correct answer is...

Neither door pillar nor Max cold pressure molded into the side wall.
Don't exceed what is molded into the side wall.

Weigh the truck axle by axle "as used", get a set of load/pressure tables, look up your tires' size and load - DONE.
If you are sloppy/lazy about tire pressures add a couple of psi to accommodate your habits and allow for slow/slight leaks - else check and adjust monthly.

 

[Reg]

Agreed. ALWAYS go by the tire and YES the recommend max inflation pressure is the RECOMMENDED pressure at all times. If the tire says 44lbs, put at 44lbs and keep it there.

Thanks
Craig
TheTrailerGuy
Stateline Trailers

No, just NO !

The ONLY time you should use this pressure is if you are carrying the max rated load - which is a marginal condition anyway and is to be avoided.

 

[silvertramp]

I've been running max sidewall pressure on my 1/2 tons & motorcycles for years. I get even wear & long life. That's my story & I'm stickin' to it.

 

[Dmace]

I ignore the useless door sticker since that is set for a wide variety of uses and people and not specific for YOUR driving habits or usage. Also, it's specific for the tire the vehicle came with and I typically go with a higher ply or larger tire size than normal. I find the door sticker number always leaves the tires under-inflated and you will notice the outsides of the tires wearing faster than the center plus the handling stinks.

I run my tires about 10% less than the max listed on the sidewall (ex: 40 psi in my truck tires rated at 44 psi). I don't run the max because if you do then you could easily run well over the max with a change in air temp and/or tire temp from driving. For example, we took a vacation to Florida and drove there (1400 miles). I put the tires up to the max 42 psi figuring we would get better gas mileage. 300 miles later and about 25 degrees warmer, I check the tires at a gas station and they were all at 50 psi. One good pothole and one of those tires could easily blow out a sidewall.

In the winter, I run a little less than normal for a wider contact patch and better snow/ice traction.

 

[SPYDERLK]

Take a good look at them loaded and air them to the sidewall rating or til they stand proud - wecf. If they dont stand up at rated pressure you are overloading the tire.
larry

 

[SPYDERLK]

Nitrogen is also used in aviation to eliminate oxygen in the tires. From AERO : Wheel and Tire Servicing

What is the issue with air % oxygen? Are there actually documented cases of igniting rubber powder in air at tire pressures.
larry

 

[oldyellr]

What is the issue with air % oxygen? Are there actually documented cases of igniting rubber powder in air at tire pressures.
larry

Methinks selling nitrogen to inflate tires is a bit of a scam. After all, air is about 80% nitrogen anyway. Sure, you're it's supposed to contain no water vapour, but there are drying systems for compressed air too. It doesn't matter if what's inside the tire, air or nitrogen, if you run it flat and it catches fire, there's plenty of air on the outside to let it burn.

 

[Mace Canute]

What is the issue with air % oxygen? Are there actually documented cases of igniting rubber powder in air at tire pressures.
larry

From the link I posted:

In addition, Boeing has received reports of three confirmed cases and other suspected cases in which a wheel/tire assembly exploded when the oxygen in air-filled tires combined with volatile gases given off by a severely overheated tire. In one case, the tire became overheated as a result of a dragging brake, and the wheel/tire assembly exploded when it reached the auto-ignition temperature. In another case, a wheel/tire assembly explosion in the wheel well during flight was suspected in the catastrophic loss of one airplane. A similar explosion caused severe damage to two others.

As a result, the U.S. Federal Aviation Administration issued Airworthiness Directive 87-08-09 requiring that only nitrogen be used to inflate airplane tires on braked wheels. However, tires may be topped off with air in remote locations where nitrogen may not be available if the oxygen content in the tire does not exceed 5 percent by volume.