One Tire Pressure For All

[robertkathy]

Originally Posted by Crasher

What does the pressure of tires on an oil truck in NY have to do with any motorhome in any state??? Is he more informed than the engineer who designed and tested the tires for correct pressure for a given load?.

he was a safety inspector yes he mainly does oil truck but was at the scale and we got talking he checked the weight and the charts checkedwith the tire manufactor and told me what the best recommended pressure should be

[arcaguy]

Originally Posted by SlowJoe

I don't think it's a good idea to ask the tire to become part of the suspension and absorb bumps by reducing it's pressure.

Whether you ask it too or not the tire is part of the suspension system. Actually it's the most important part, it keeps the contact with the road. As to making it a spring, it is by nature a spring, specifically an air bag. As for big rigs not changing their tire pressure it is a convenience thing. Their weights are constantly changing, most times on a daily basis, RVs not so much. Again I probably won't change any one's mind. If you believe the earth is flat no amount of evidence will change your mind, it's the nature of humans.

[Mudfrog]

Originally Posted by Gordon1152

This topic has been batted around for decades, but I'm curious what experience people have had setting one tire pressure for all of the coach tires?



I ran 110 all the way around on my last DP and intend to do the same with this one because I can't see the downside other than possibly a harsher ride. Call me lazy, but there's no risk of under inflation wear or premature failure and it sure is easy to remember ...

Ours is a smaller rig than most and runs on 19.5s. The federal weight sticker shows to run all 6 tires at 75 psi, the pressure needed to support the motorhome at its full gvw. For grins, I just run em all at 80 psi and call it a day. Not lazy at all, but like you, easy peasy to remember.

[robertkathy]

Originally Posted by richard5933

Why? At best you will have a harsher ride than necessary. At worst you'll have increased tire wear, worse handling, and poorer breaking.

It amazes me that engineers who spend their careers coming up with the inflation charts are dismissed so easily.

my sticker calls for 95 and 105 psi i have extra weight due to what i haul along with the reasons of the other post.

[Crasher]

The only correct pressure for maximum traction, longevity and quality of ride is the pressure stated in the load inflation charts. I proved that to myself on our last set of tires. Anything different will compromise one of the above. The last set of Michelins I ran, I kept the steer tires at the minimum required for the load which was close to their maximum carrying capacity. The drive tires required 80 psi, but I carried 90. After 50,000 miles, the steer tires were worn even across the tread, while the drive tires were worn 50% more on the inner ribs that the outer ribs, reflective of being over inflated for the load they were supporting. FWIW, the placard on my coach said 110 psi for all tires which would have been even worse for the drive, but also 5% under inflated on the steer.

Regardless of what the tire engineers state, many RVers will have their own reasons and justification to think their plan is a better one.

[Kiss4aFrog]

Originally Posted by robertkathy

it was recommend by a safety inspector for oil trucks in ny state

I can't tell if we're being trolled or not?
You just have to go with what you feel is safe and hope you're not wrong.
This is like trying to get agreement on what's the best oil, or filter or ...

[txcpl]

When we purchased our used MH, the tires had 110 lbs all the way around. The door tag said 120 lbs. After a year of driving that rough riding MH, the wife was ready to sell. After gathering info from this site and others, I checked out the tire inflation charts, and using the weight info from the CAT scales, I dropped the pressure to 90 & 95 lbs. What a difference in the ride, and the road noise dropped substantially. I now assume the tag on the door is MAXIMUM inflation, and I have learned that those tags cannot cover all applications.

I have learned a lot from this site and others over the years, and am thankful I don't have to constantly re-invent the wheel.

[wildtoad]

As far as I know the tire manufacturers chart will tell you the minimum pressure REQUIRED to carry the weight. Period. It is NOT perhaps the best choice of pressures to use for tire wear, tire longevity, MPG. In my case the tire chart based on my weight indicates I can use mid 80’s. The placard from Newmar says 92 ( no correlation to axle weights ) The F53 specs says 92 or 95 depending on if it’s an upgraded front axle. In conversation with a Goodyear rep ( my tires ) they indicated to use 95 for overall tire performance and twice urged me NOT to set PSI below what is on the federal placard.

I fully understand how people can get confused over tire PSI and why there are so many threads on the subject.

My tires are G670 245/19.5. Here’s one of the responses from Goodyear. It may not be relevant for your tires.

From Goodyear

“Based on the weights when fully loaded, YES, you are below our chart pressure. The G670 is technically considered a commercial tire and by industry standards a commercial tire should not be run below 20% of its max inflation pressure(110psi). From your actual weights and using our chart 80 psi would be the lowest setting. This psi will still handle the load just fine but keep in mind, that low of a pressure might start to develop some shoulder wear due to the flatter footprint the tire makes when contacting the ground, and an increase in heat buildup due to the additional flex in the sidewall. What we have seen from past experience with this particular size is that 95 psi is the sweet spot. The benefits to this setting will be less sidewall flex which will reduce the amount of heat build up while driving and you will get more life out of the tire and should see good fuel economy. At worst case I would not go below vehicle placard. In the event of an accident or failure, you could be liable.”

[Gordon1152]

For the record, I'm running Michelin's on my new rig and 120 is the max cold pressure. We're not full timing yet nor have we fully figured out the right stuff to carry when we do travel, but I will commit to getting weighed next time we load up.


Beyond that I keep falling back to the fact that 110 is not over inflated and will handle any reasonable weight we throw at it. Under inflated tires fail, well inflated tires don't ...

[Domo]

Let me be the FINAL authority on air pressure, tire wear, usage, load distribution, and general ride and suspension issues...

--->> My salesman told me... {fill in your favorite}

[TonyMac]

Originally Posted by robertkathy

my sticker calls for 95 and 105 psi i have extra weight due to what i haul along with the reasons of the other post.

Your sticker calls for a certain size and rating of tire and a certain max weight to match those 95/105 pressures. And you have "extra weight" so you run higher pressures? Where did you get those pressures? If you got them from the sidewall, they are not the max pressures. They are the MIN pressures to run the max weight.

If your weights are above those stated on the sticker, you are exceeding the capabilities of your rig. If your weight are at your sidewall limits, you are AT you max tire weights. G-luck.