Proper tire inflation

[Mr_D]

Originally Posted by FastEagle

No. My statement about who sets tire pressures is correct across all lines.


Vehicle manufacturers set recommended tire pressures.　
　
If you will research deeply you will find that when retailers use load inflation charts to manipulate tire pressures for RV trailers or motorhomes those pressures cannotbe less than the vehicle manufacturer's recommendations (Your Firestone reference points that out). Unless, Replacement tires of another size have been used and a new recommended tire pressure has been set for those tires. The easiest reference to use to understand the resetting of recommended tire pressures is Bridgestone's. It's easy to read and points out all the pitfalls most inexperienced installers will fall into.

FastEagle

ONLY TRUE for car tires, we're talking about RV/truck tires. There is a difference!!

From Michelin, their quick summation of two pages of their Recreational Vehicle Tire Guide:
"The amount of air pressure you need to use depends on the weight of your full-loaded vehicle. So, you cannot determine your correct air pressure unless you know your vehicle's actual weights"
"A tire that is overinflated for the load that it is carrying will also contribute to a harsh ride, uneven tire wear, and will be more susceptible to impact damage."

From Toyo's Recreational Tire Vehicle Guide
"The amount of air pressure in a tire determines the load that can be carried safely. Every Toyo Tire will have the maximum load and inflation molded in the sidewall of the tire. THIS LOAD AND INFLATION RATIO SHOULD NEVER BE EXCEEDED SINCE THIS CAN CAUSE HANDLING PROBLEMS, IRREGULAR WEAR, AND COMPONENT FAILURE. The proper amount if air pressure is always determined by the weight of your RV fully loaded. This weight takes into account all liquids, supplies, and passengers. Tires on RV applications are subject to a variety of more severs conditions when compared to automobiles or trucks. Because of many chassis and optional equipment differences, it is possible for an RV to be within its Gross Vehicle Weight Rating (GVWR), but overloaded when taking into consideration the weight if each wheel position. The only way by which you can know the safe load and inflation pressure for your RV is to know the actual weight of each wheel position under actual loaded conditions. Underinflation of a tire can cause poor handling, irregular wear, and decreased fuel economy. It also causes extreme heat build-up within the components of the tire, which can lead to failure. Overinflation of the tire causes deformation of the contact patch resulting in crowning of the center tread. This causes handling problems such as reduced traction, irregular wear, and an increased chance for impact damage."

From Firestones RV brochure:
All members of the Recreational Vehicle Industry Association (RVIA) are required to place an additional label on the vehicles they manufacture. It lists information not
found on the Federal Dataplate and supersedes the Federal Dataplate, which usually covers only the basic vehicle chassis.

There are two versions of the RVIA label, depending on whether the vehicle was manufactured from September 1996 through August 2000, or after September 1, 2000. There are also separate versions of the label for motor homes and for trailers, including “fifth wheel” trailers.

[Ed-Sommers]

Whomever comer out with tire pressures, it is only a recommendation.

There are many considerations taken into account when making these recommendations, but the three given the most consideration, from the user, are longevity, comfort, and safety.

For longevity, a tire has to run with all it's foot running flat, and that can be checked with a chalk ling across the tire and then the line checked after a short drive. Chalk in the middle,too much air, only on the sides of tread, too little air. If all the chalk gone, tire running great for that longevity.

For comfort, less pressure will give you a softer, and quieter ride.

For safety, more pressure will provide less probability of tire separating from the rim in an emergency swerve to avoid a head on collision, among other safety factors.

I bring all this up only to illustrate that a recommendation is given only after taking these, and other, factors into consideration TO VARYING DEGREES, by the recommending entity.

YOU may find different factors with favor, and adjust pressure accordingly, to a certain degree.


Ed

[CD]

Originally Posted by Ed-Sommers

Whomever comer out with tire pressures, it is only a recommendation.

There are many considerations taken into account when making these recommendations, but the three given the most consideration, from the user, are longevity, comfort, and safety.

For longevity, a tire has to run with all it's foot running flat, and that can be checked with a chalk ling across the tire and then the line checked after a short drive. Chalk in the middle,too much air, only on the sides of tread, too little air. If all the chalk gone, tire running great for that longevity.

For comfort, less pressure will give you a softer, and quieter ride.

For safety, more pressure will provide less probability of tire separating from the rim in an emergency swerve to avoid a head on collision, among other safety factors.

I bring all this up only to illustrate that a recommendation is given only after taking these, and other, factors into consideration TO VARYING DEGREES, by the recommending entity.

YOU may find different factors with favor, and adjust pressure accordingly, to a certain degree.


Ed

The info about using chalk is good except you have it reversed. When chalk is gone in the middle there is too much pressure etc.

[FastEagle]

When referring to DOT certified tires with an accompanying tire placard the term "Recommended tire pressure" found on the tire placard or certification label Means, CORRECT TIRE PRESSURE.

Never operate your vehicle with tires inflated to
less pressure than specified on the vehicle placard,
NO MATTER WHAT THE LOAD.
Never inflate your tires above the maximum pressure
shown on their sidewalls. (Bridgestone)

FastEagle

p.s. When manipulating a heavy vehicle's tire pressures for load conditions the vehicle manufacture should be the first expert point of contact. After all, Tire manufacturers build tires for their use and distribution.