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Trailer tire Pressure


Broncohauler

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I know we discussed this before but not finding it in the resource guide

What do you guys recommend for tire pressure?

17.5 tires Sailun S637. 215/75R17.5 Max load rating 4805at 125psi

3axles

About 19,000 lbs loaded

Tires max 125 psi I run them around 115psi and I'm finding everything jostled around in the trailer pretty heavily where I did not with the 15 inch tires.

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Bronco,

 

Can't get my load chart to attach but figure pin weight at 20% so about 3800#. So rough estimate is 15,200# divided by four tires which approximates 3800# per tire unless you have weighed individually. My chart says between 95 and 100 psi will carry that load. I would personally be a little more to the high side.

2006 Volvo 780 "Hoss" Volvo D12, 465hp, 1650 ft/lbs tq., ultrashift

Bed Build by "JW Morgan's Custom Welding"

2017 DRV 39DBRS3

2013 Smart Passion Coupe "Itty Bitty"

 

"Don't go around saying the world owes you a living. The world owes you nothing. It was here first!"

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I think that should be 15,200# "divided by six tires" rather than "divided by four tires" if you have three axles. That will drop your inflation pressures quite dramatically which should improve your ride a bit. I don't have a load chart handy.

 

Geo

George,
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I think that should be 15,200# "divided by six tires" rather than "divided by four tires" if you have three axles. That will drop your inflation pressures quite dramatically which should improve your ride a bit. I don't have a load chart handy.

 

Geo

Yeah that's right so with six tires would be about 2530# and cold inflation would be in the 80's.

Try this link.

http://www.goodyeartrucktires.com/pdf/resources/publications/2010_loadinflation.pdf

2006 Volvo 780 "Hoss" Volvo D12, 465hp, 1650 ft/lbs tq., ultrashift

Bed Build by "JW Morgan's Custom Welding"

2017 DRV 39DBRS3

2013 Smart Passion Coupe "Itty Bitty"

 

"Don't go around saying the world owes you a living. The world owes you nothing. It was here first!"

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From the Michelin RV Tire Guide

 

"Overinflation, on the other hand, will reduce the tire’s

contact area with the road, which reduces traction,

braking ability, and handling. A tire that’s overinflated

for the weight it’s carrying is more prone to a harsh ride,

uneven tire wear, and impact damage."

Use the correct weight/inflation guide for you brand and size - and believe what they tell you!

Dennis & Nancy
Tucson, AZ in winter, on the road in summer.

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(Replaced '05 smart first loaded in '06

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Before putting the Sailun S637's on my trailer, I was told by a current tire store manager and a retired 30 year tire store owner how great these tires seem to hold up and give great service. Both men said the only complaint they've ever gotten about these tires is the rough ride. When I took my trailer in to have them mounted I was shocked and amazed how much heavier the tire bead and the sidewalls are on the Sailuns, compared to the BF Goodrich's they took off my trailer. It makes sense to me that they would have to ride rougher compared to a softer sidewall with the same air pressure in both.

 

Ed

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Sometimes the caulk on the tire trick works to get you in the ball park for tire pressure when you don't have a resent weight.

Thank you guys for all your advice I'm gonna start around 100 psi

hey Mr seas I've told many people about the chalk idea don't know why I didn't remember it myself thank you.

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Bronco,

 

Sorry, in my first post I overlooked the line where you had three axles.

2006 Volvo 780 "Hoss" Volvo D12, 465hp, 1650 ft/lbs tq., ultrashift

Bed Build by "JW Morgan's Custom Welding"

2017 DRV 39DBRS3

2013 Smart Passion Coupe "Itty Bitty"

 

"Don't go around saying the world owes you a living. The world owes you nothing. It was here first!"

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Tire guy on one site says divide sidewall load rating by max psi to get Pounds of load by required psi. 6000/100= 60 lbs per psi. 4000 lbs would require 67 psi for even tread wear.

 

Sounds reasonable.

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Why all the various "home brew" methods of learning the minimum CIP to set the tires to.

Sailun tires are "Commercial" type not ST or LT type so yes they are HD tires.

 

Find a Load / Inflation chart for that size and after confirming your actual individual tire loading use the heavier end of each axle to learn the MINIMUM CIP to use. I also suggest you add 10% to the table minimum so you aren't chasing your tail whenever the temperature drops and you discover you need to add a few psi.

Check out my Blog www.RVTireSafety.NET

 

I serve on Tech Advisory board of FMCA as their Tire Expert.

Give three different seminars on tires at RV events and I also give three seminars on Genealogy too.

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  • 2 weeks later...

Thank you all for your help with finding a comfortable tire pressure. :)

 

I set the trailer tires cold at 90 psi at 85 outside temp and 1400ft elevation. The outside air temp got up to 95 deg and the tires highest temp went up to 108 deg.

Climbing the hills we topped out 8000ft elevation

And the highest air pressure was 102 psi.

I did notice that we gained 2psi climbing from 700ft to 8000ft.

 

The truck and trailer rode better than I ever remember.

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  • 2 months later...

I called Goodyear to get the web address of there inflation table. I have all 4 of my 5ver wheels weighed and 3 were were at 3800 and one was at 4200. So I thought I would set them all to carry 4500 lbs. My 5ver is plated at 125 psi. So the Goodyear rep said set them at 125 psi. Even if that is over inflated by your load/psi chart. YUP,she said. So now I am a little confused. Thanks for your advise.

2015 Ram 3500 RC DRW CTD AISIN 410 rear

2016 Mobile Suites 38RSB3

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I called Goodyear to get the web address of there inflation table. I have all 4 of my 5ver wheels weighed and 3 were were at 3800 and one was at 4200. So I thought I would set them all to carry 4500 lbs. My 5ver is plated at 125 psi. So the Goodyear rep said set them at 125 psi. Even if that is over inflated by your load/psi chart. YUP,she said. So now I am a little confused. Thanks for your advise.

Rynosback,

 

I spoke to Goodyear several years ago about a different issue but had been using their charts for inflation (I have 17.5 inch G114s). I was noticing about a 16% increase in pressure (100 psi to 116 psi) as my tires heated up at highway speeds (for me 62mph). Temps stayed good. All of their literature and other references on the web said that increase should be only 3 - 5% ( 3 - 5 psi). The first few folks I spoke with stumbled and bumbled when I asked about proper inflation pressures and then this increase. When pressed they finally connected me to an engineer at their testing facility. He said the 3 - 5% was not accurate and what I was seeing was normal on larger, heavier tires. He also advised me to use the inflation charts for my weights as he had helped develop these at their facility. Moral to the story: you're going to get multiple answers from the manufacturer and you have to choose which info to take. I went with the engineer.

2006 Volvo 780 "Hoss" Volvo D12, 465hp, 1650 ft/lbs tq., ultrashift

Bed Build by "JW Morgan's Custom Welding"

2017 DRV 39DBRS3

2013 Smart Passion Coupe "Itty Bitty"

 

"Don't go around saying the world owes you a living. The world owes you nothing. It was here first!"

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I called Goodyear to get the web address of there inflation table. I have all 4 of my 5ver wheels weighed and 3 were were at 3800 and one was at 4200. So I thought I would set them all to carry 4500 lbs. My 5ver is plated at 125 psi. So the Goodyear rep said set them at 125 psi. Even if that is over inflated by your load/psi chart. YUP,she said. So now I am a little confused. Thanks for your advise.

http://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

Rocky & Sheri Rhoades
'01 Volvo 770
2016 DRV Mobile Suites, Houston
HERO Makers Ministry

 

30495168531_143d8fb8d6_m.jpg

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Rynosback,

 

I spoke to Goodyear several years ago about a different issue but had been using their charts for inflation (I have 17.5 inch G114s). I was noticing about a 16% increase in pressure (100 psi to 116 psi) as my tires heated up at highway speeds (for me 62mph). Temps stayed good. All of their literature and other references on the web said that increase should be only 3 - 5% ( 3 - 5 psi). The first few folks I spoke with stumbled and bumbled when I asked about proper inflation pressures and then this increase. When pressed they finally connected me to an engineer at their testing facility. He said the 3 - 5% was not accurate and what I was seeing was normal on larger, heavier tires. He also advised me to use the inflation charts for my weights as he had helped develop these at their facility. Moral to the story: you're going to get multiple answers from the manufacturer and you have to choose which info to take. I went with the engineer.

I believe that is what Trey would say also.

Rocky & Sheri Rhoades
'01 Volvo 770
2016 DRV Mobile Suites, Houston
HERO Makers Ministry

 

30495168531_143d8fb8d6_m.jpg

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Went through this myself with my 17.5 tires Finally decided when I'm fully loaded with my bronco in the trailer 90 psi works best. And when we go camping with an empty trailer 85 psi.

I noticed on our last trip running the freeway and tight curvy mountain roads from sea level to 9000 feet My tires would go from 85 psi up to a max of 94 psi and the tire temperature don't remember exact numbers but was staying fairly consistent with outside air temperature

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I will say also watch the time a day and your weather when filling your tires.

Iwas in the desert over the holidays our trailer sitting for four days. When I did my pretrip and started up the truck I noticed the tires sitting in the shade on one side of the trailer where at 85 psi. And the tires on the other side of the trailer in the hot sun were at 95 psi

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I will say also watch the time a day and your weather when filling your tires.

Iwas in the desert over the holidays our trailer sitting for four days. When I did my pretrip and started up the truck I noticed the tires sitting in the shade on one side of the trailer where at 85 psi. And the tires on the other side of the trailer in the hot sun were at 95 psi

I've noticed the same thing. I set my alarm pretty close to my target pressure, like 10# lower. On a cool morning I may get the buzzer until I turn the rig around and let the sun warm the other side.

 

Several years ago, I put together a motorcycle rally in Colorado. Some of the guys would check air pressures every morning, never giving a thought to the 40-50 degree temp. increase later in the day, not the fact that we'd have 6,000' elevation changes. Not that they shouldn't check, but be aware of all the factors.

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The correct tire inflation pressure for your trailer tires was set by the trailer manufacturer and displayed on the trailer’s certification label, tire placard and in the owner manual. The recommended pressures found there provides the load capacity from the OE tires to satisfy what the vehicle manufacturer deemed appropriate for the Original Equipment tires.

 

Establishing the correct recommended inflation pressure for all replacement tires is a necessary function as we all have to have a starting point for correct inflation.

 

When plus sizing with replacement tires there is an approved set of industry standards to guide you in the process. Once the plus sized tires are selected and deemed a safe fitment for the trailer, new recommended tire inflation pressures must be established. As a minimum the plus sized tires must provide the load capacity of the OE tires. Once a psi value has been selected to provide the necessary (minimum) load capacity, a notation about new tire size and recommended inflation pressures can be made in the owner manual. Along side of the trailer’s certification label an auxiliary tire placard can be displayed with the new tire/rim sizes and the new recommended inflation pressures. (Auxiliary tire placards are allowed by NHTSA for this situation).

 

Never use inflation pressures less than what has been recommended by the vehicle manufacturer. It’s an industry standard that is just not done to any tires originally fitted using FMVSS regulations. Truck tires used on any type of RV are fitted in accordance with FMVSS regulations. Large RV tires used on Motor Homes are fitted in accordance with FMVSS regulations. When in doubt, read the individual regulations. For the Trailer in this thread its easily found by typing 571.120 into a search engine.

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