Tire pressure question

[redhooker]

As someone that has experienced every trailer tire failure imaginable-I used to tow boats at high speeds across the country tournament fishing with 100 other yahoos-we messed up some tires let me tell you. One year I replaced 6 tires on a single axle trailer due to 2 flats and 4 bubbled sidewalls. I was running 35 psi and loaded to about 30% of tires rated capacity with a saltwater flats boat. Denmans, GYMs, Carlisles, you name it I bought it. I won't even go into my hub catastrophes-dipping trailers into salt water is always a recipe for eventual disaster.

The suggestions above to inflate to max pressure is the best advice you will ever get. I have heard every form of advice from tire dealers imaginable, but anything less than max is asking for trouble. The tires run coolest at max pressure, period. The sidewalls carry the least stress at max pressure. Let the air do the heavy lifting and save your sidewalls (they have the least plies). The only downside to max pressure is a slightly stiffer ride, but since doing this I went from multiple blowouts or sidewall bubbles yearly, to NONE over the last 5 years. There is no other downside to running max pressure, even if you are at 25% of tires capacity. I experience relatively even tread wear especially with radials. I used to blame China for my tire woes, but now realize I was causing most of those failures. I run chinese tires as well as canadian but no problems anymore. On any trailer, I only run MAX cold pressure. All the research states almost all tire failures are from over loading or under inflating. Best way to avoid that is to give your tires the ability to handle all the weight they can, even if you don't think you need it.

[taken]

I'm with Jim. Max pressure. Less sidewall flex. Less heat. More longevity. KISS theory...

[Mr_D]

The pressure on the sidewall of a Michelin RV tire and many others is not the "Maximum" the tire should ever have (unlike car tires) it is the minimum to support the maximum rated carrying capacity of the tire.

From the Michelin RV Tire Guide:

"If you look at the tire's sidewall, you'll see the maximum load capacity allowed for the size tire and load rating, and the minimum cold air inflation needed to carry the maximum load."

From page 6 of the GoodYear RV Tire and Care Guide:

"How much air is enough?
The proper air inflation for your tires depends on how much your fully loaded RV or trailer weighs. Look at the sidewall of your RV tire and you’ll see the maximum load capacity for the tire size and load rating, as well as the minimum cold air inflation, needed to carry that maximum load."

From TOYO:

Q: What are the consequences of inflating the tires to accommodate the actual loads?
A: If the inflation pressure corresponds to the actual tire load according to the tire manufacturer’s load and pressure table, the tire will be running at 100% of its rated load at that pressure. This practice may not provide sufficient safety margin. Any air pressure loss below the minimum required to carry the load can result in eventual tire failure.

But then they go ahead and publish a weight/pressure chart allowing lower pressure for RV's!!

From the August 2010 Motorhome Magazine "Tread Carefully" tire article:

The maximum load capacity allowed for the size tire and load rating and the minimum cold air inflation needed to carry that maximum load are located on the tire’s sidewall.

[wingnut60]

FastEagle,
I too, would have been impressed with the tires on that Landmark, if only they had put 8k axles under it also...
Joe

[FastEagle]

Originally Posted by Mr_D

The pressure on the sidewall of a Michelin RV tire and many others is not the "Maximum" the tire should ever have (unlike car tires) it is the minimum to support the maximum rated carrying capacity of the tire.

“At the manufacturer's option, the shown inflation pressure may be as much as 10 psi (69 kPa) greater than the inflation pressure corresponding to the specified maximum load.”

All ST & LT tires have an extra 10 psi in reserve. They do not provide any extra load capacity but they are there.

You can find that information in FMVSS 571.139.

FastEagle

[Mr_D]

Originally Posted by FastEagle

“At the manufacturer's option, the shown inflation pressure may be as much as 10 psi (69 kPa) greater than the inflation pressure corresponding to the specified maximum load.”

All ST & LT tires have an extra 10 psi in reserve. They do not provide any extra load capacity but they are there.

You can find that information in FMVSS 571.139.

FastEagle

Not sure what you're getting at as what I posted is a direct copy and paste from the various tire manufacturers published info and don't pertain to LT or ST tires.

[FastEagle]

Originally Posted by Mr_D

Not sure what you're getting at as what I posted is a direct copy and paste from the various tire manufacturers published info and don't pertain to LT or ST tires.

LT tires have their maximum allowed load capacity molded into their sidewalls. They also have the minimum inflation pressure needed to support that load capacity. That's kind of what Michelin is saying. What I posted is saying the tire can take another 10 psi but only at the tire manufacturer's option. It is seldom used. An example is the Goodyear bulletin allowing another 10 psi in their Marathon ST tires to allow them to gain another 10 MPH. Even though GY has approved that action the vehicle manufacturer would have to also approve such action.

FastEagle

[FastEagle]

[QUOTE=Mr_D;2556823]The pressure on the sidewall of a Michelin RV tire and many others is not the "Maximum" the tire should ever have (unlike car tires) it is the minimum to support the maximum rated carrying capacity of the tire.

From the Michelin RV Tire Guide:

[QUOTE]

On another not; Michelin does not address tires for RV trailers as they do not build any. The fitment rules for motorized vehicles differ from the rules for RV trailer tire fitments. However, the information on the sidewalls of the larger RV/truck type tires used on motorized RVs mimic each other.

FastEagle

[wandering1]

The PSI is on the sidewall is there for a reason. Running tires over or under inflated causes excess heat which damages the tire. If the PSI on the sidewall says 110 then inflate to 110. Not a good question for a forum where there are a lot of tire expert wannabes giving their personal opinions. Contact the tire manufacturer and get the facts.

[drfife]

There are several tire expert wannabes on this forum....

[FastEagle]

Originally Posted by wandering1

The PSI is on the sidewall is there for a reason. Running tires over or under inflated causes excess heat which damages the tire. If the PSI on the sidewall says 110 then inflate to 110. Not a good question for a forum where there are a lot of tire expert wannabes giving their personal opinions. Contact the tire manufacturer and get the facts.

But, your statement above about the 110 psi is a personal opinion.

The correct answer and correct recommended tire pressure is - by all industry and safety standards - found in your vehicle's owner's manual, on the tire placard and certification label. Deviations will also be found in the vehicle owner's manual.


FastEagle

[drfife]

I rest my case....

[taken]

Originally Posted by wandering1

The PSI is on the sidewall is there for a reason. Running tires over or under inflated causes excess heat which damages the tire. If the PSI on the sidewall says 110 then inflate to 110. Not a good question for a forum where there are a lot of tire expert wannabes giving their personal opinions. Contact the tire manufacturer and get the facts.

Yes, it's there for a reason but not the one you state... at least not in the case of tow vehicles. It's the max pressure the tire can handle. Not the recommended tire pressure. For example, I have the same tires on the front of my truck as the rear but as per Ford, they run at 65 on the front and 80 on the rear based on the typical load of each location. (I drop my rears to 65 in the off towing season...) The same tires come on a 250 but there, Ford has them at 65 all around. Running a tire at max inflation when the load doesn't require it will cause premature wear in the center of the tire as it's not riding flat on the pavement.

Although, in a trailer situation, I agree with Jim that lateral forces, sway, and scrubbing will be better handled by max pressure giving max sidewall stability.

[twinboat]

taken,

I have a hard time, believing that running your tires at the manufactures recommendation, will cause center tread wear.

These LT tires are used on delivery trucks every day. They don't change the pressure as the truck gets lighter.

I understand lowering the pressure to soften the ride, but too low and now you are under inflated.