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09-16-2017, 11:14 AM
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#1
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Senior Member
Monaco Owners Club Newmar Owners Club
Join Date: Dec 2014
Location: out west
Posts: 1,061
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Weight & tire PSI question
what would the proper PSI be for my tires:
Front Toyo M144 22.5/295/80R 11,760 lbs. front axle
Rear Duel Goodyear 670RV 22.5/295/80R 22,520 lbs.
Towing a Jeep Wrangle 4640 lbs.
For those of you in the know.
I have been keeping all my tires at 100 PSI.
Thanks
__________________
2017 Dutchstar 4369 Spartan Chassis, 2200W Solar, 1200AH Lithium Batteries, Active Air
2022 Jeep Grand Cherokee, Roadmaster Sterling, AF1
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09-16-2017, 11:26 AM
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#2
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"Formerly Diplomat Don"
Newmar Owners Club
Join Date: Apr 2005
Location: Moorpark, Ca.
Posts: 23,909
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Here's the chart..... http://www.goodyearrvtires.com/pdfs/rv_inflation.pdf
Yours falls into an usual category where the rear calls for more air than the front. 100 front and 105 rear. USUALLY, the rears are inflated 5-15 pounds less.
Whoops......I missed the Toyo's on the front. Seems like pressures are still the same.
__________________
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor
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09-16-2017, 11:39 AM
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#4
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Senior Member
Join Date: Dec 2013
Location: Lake Havasu City, AZ & Plover, WI
Posts: 6,403
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From the load charts: Front 100-105, Rear 105-110. This is a good start, but a four position weight would be better. What are the GAWR front and rear?
__________________
2006 Monaco Executive 44 Denali
2013 43 QGP Allegro Bus ( SOLD )
2013 Avalanche
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09-16-2017, 09:07 PM
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#5
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Senior Member
Monaco Owners Club Newmar Owners Club
Join Date: Dec 2014
Location: out west
Posts: 1,061
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Quote:
Originally Posted by Crasher
From the load charts: Front 100-105, Rear 105-110. This is a good start, but a four position weight would be better. What are the GAWR front and rear?
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GAWR Is 12,800 front and 23,000 rear. I'm very close to the limit with 100 gal of water, 40 gal propane (which I will never use up) and full gas tank 109 gal which I was when weighed.
Probably should add 10lbs to the rear. 100 front 105 rear whould be better perhaps.
Thanks all for the input.
__________________
2017 Dutchstar 4369 Spartan Chassis, 2200W Solar, 1200AH Lithium Batteries, Active Air
2022 Jeep Grand Cherokee, Roadmaster Sterling, AF1
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09-17-2017, 05:10 AM
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#6
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Senior Member
Join Date: Dec 2013
Location: Lake Havasu City, AZ & Plover, WI
Posts: 6,403
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Quote:
Originally Posted by Golfer Guy
GAWR Is 12,800 front and 23,000 rear. I'm very close to the limit with 100 gal of water, 40 gal propane (which I will never use up) and full gas tank 109 gal which I was when weighed.
Probably should add 10lbs to the rear. 100 front 105 rear whould be better perhaps.
Thanks all for the input.
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Keep in mind that the axle weight might not be equally divided between sides. It's not uncommon to see an axle 1000# heavier on one side that the other. What does that do to the psi requirement?? Only a four position weight can get you the correct pressures.
__________________
2006 Monaco Executive 44 Denali
2013 43 QGP Allegro Bus ( SOLD )
2013 Avalanche
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09-17-2017, 05:22 AM
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#7
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Senior Member
Join Date: Aug 2016
Posts: 3,400
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It's also a good practice and most folks here do this, is once you determine your proper PSI add at least an additional 5lbs. for a fudge factor and possible weight creep.
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09-17-2017, 11:13 AM
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#8
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Senior Member
Monaco Owners Club Newmar Owners Club
Join Date: Dec 2014
Location: out west
Posts: 1,061
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Quote:
Originally Posted by Crasher
Keep in mind that the axle weight might not be equally divided between sides. It's not uncommon to see an axle 1000# heavier on one side that the other. What does that do to the psi requirement?? Only a four position weight can get you the correct pressures.
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I had a four corner weight done at Escapees a year ago or so. The weights were as follows:
R Front 5920 R Rear 11250
L Front 5850 L Rear 10400
then 11,800 21,650
now 11,700 22,520
New different brand tires (Toyo) in the front since then and weights have increased a bit over time. Added two batteries to the passage rear side. Towing a different heavier car now too. Escapees said 95 in the front and 100 in the rear back then.
Thanks for the input guys.
Steve
__________________
2017 Dutchstar 4369 Spartan Chassis, 2200W Solar, 1200AH Lithium Batteries, Active Air
2022 Jeep Grand Cherokee, Roadmaster Sterling, AF1
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09-18-2017, 02:27 AM
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#9
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Senior Member
Join Date: Sep 2009
Posts: 1,536
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Tire industry standards are consistent across the board. Different manufacturers may say it differently but in the end they all mean the same thing.
If your Motor Home has a federal certification label installed by the final stage manufacturer and it has recommended cold inflation pressures for the tires depicted on it, it was built to FMVSS standards and all industry standards applicable to FMVSS standards apply.
Many MHs are fitted with large commercial grade tires. That does not mean commercial regulations can be applied. Commercial standards do not have recommended cold inflation pressures.
Tire industry standards are found in just about all major tire manufacturer’s publications or in PDF files on the WWW. Here is a quote from page #7 in the attached reference.
“The placard indicates the minimum inflation pressures which must be maintained.”
http://www.michelintruck.com/assets/...e_Warranty.pdf
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09-18-2017, 07:10 AM
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#10
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Senior Member
Join Date: Dec 2013
Location: Lake Havasu City, AZ & Plover, WI
Posts: 6,403
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Quote:
Originally Posted by FastEagle
Tire industry standards are found in just about all major tire manufacturer’s publications or in PDF files on the WWW. Here is a quote from page #7 in the attached reference.
“The placard indicates the minimum inflation pressures which must be maintained.”
http://www.michelintruck.com/assets/...e_Warranty.pdf
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Keep in mind that the manufacturer needs to protect their behinds, so they assume that the motorhome is loaded to the maximum GVWR all the time. Those are the psi values on the placard. Many MH's, especially those with tag axles are never at the GVWR. In every case the only way to achieve the best ride, handling characteristics and tire wear is to go by the tire manufacturers load inflation charts.
__________________
2006 Monaco Executive 44 Denali
2013 43 QGP Allegro Bus ( SOLD )
2013 Avalanche
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09-18-2017, 11:58 AM
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#11
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Senior Member
Monaco Owners Club
Join Date: Aug 2011
Location: Wherever we are
Posts: 389
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Quote:
Originally Posted by Golfer Guy
I had a four corner weight done at Escapees a year ago or so. The weights were as follows:
R Front 5920 R Rear 11250
L Front 5850 L Rear 10400
then 11,800 21,650
now 11,700 22,520
New different brand tires (Toyo) in the front since then and weights have increased a bit over time. Added two batteries to the passage rear side. Towing a different heavier car now too. Escapees said 95 in the front and 100 in the rear back then.
Thanks for the input guys.
Steve
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Good job getting weighed. Here's the Toyo inflation tables:
https://toyo-arhxo0vh6d1oh9i0c.stack...ion_tables.pdf
I use the same tires. I add 5 psi to the values given for the weights.
HTH,
__________________
Bob Covey
Home: 2003 Monaco Executive 43 SDDS, ISM
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09-18-2017, 01:53 PM
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#12
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Senior Member
Join Date: Sep 2009
Posts: 1,536
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Quote:
Originally Posted by Crasher
Keep in mind that the manufacturer needs to protect their behinds, so they assume that the motorhome is loaded to the maximum GVWR all the time. Those are the psi values on the placard. Many MH's, especially those with tag axles are never at the GVWR. In every case the only way to achieve the best ride, handling characteristics and tire wear is to go by the tire manufacturers load inflation charts.
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Maybe the Vehicle manufacturer is protecting their "behinds". In compliance with FMVSS standards they were told to do so by setting recommended cold inflation pressures that are appropriate for the GAWR. Tire industry standards support that statement by saying to never use inflation pressures below vehicle manufacturer recommendations.
Tire manufacturers do not set tire pressures for vehicles built using FMVSS standards. They provide charts/tables for vehicle manufacturers to use during tire selection and fitments. After market plus sized tires have their inflation pressures set to provide a load capacity equal to or greater than the OE tires provided.
It's important to remember that FMVSS standards are only going to meet approved minimal safety standards. So, an owner can always increase their tires cold inflation pressures to gain load capacity reserves. Not all fitments will provide that option and wheel and tire maximums cannot be safely exceeded.
Read FMVSS 571.120 paragraph S5.3.1.
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09-18-2017, 02:30 PM
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#13
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Senior Member
Join Date: Dec 2013
Location: Lake Havasu City, AZ & Plover, WI
Posts: 6,403
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Quote:
Originally Posted by FastEagle
Maybe the Vehicle manufacturer is protecting their "behinds". In compliance with FMVSS standards they were told to do so by setting recommended cold inflation pressures that are appropriate for the GAWR. Tire industry standards support that statement by saying to never use inflation pressures below vehicle manufacturer recommendations.
Tire manufacturers do not set tire pressures for vehicles built using FMVSS standards. They provide charts/tables for vehicle manufacturers to use during tire selection and fitments. After market plus sized tires have their inflation pressures set to provide a load capacity equal to or greater than the OE tires provided.
It's important to remember that FMVSS standards are only going to meet approved minimal safety standards. So, an owner can always increase their tires cold inflation pressures to gain load capacity reserves. Not all fitments will provide that option and wheel and tire maximums cannot be safely exceeded.
Read FMVSS 571.120 paragraph S5.3.1.
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OK. You do it your way and I'll continue to use the load inflation tables as I have been for 25 years with good results even when the load calls for a psi below the placard figure.
__________________
2006 Monaco Executive 44 Denali
2013 43 QGP Allegro Bus ( SOLD )
2013 Avalanche
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09-18-2017, 02:37 PM
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#14
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Senior Member
Join Date: Sep 2009
Posts: 1,536
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Quote:
Originally Posted by Crasher
OK. You do it your way and I'll continue to use the load inflation tables as I have been for 25 years with good results even when the load calls for a psi below the placard figure.
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It's not MY way. It's the industry's acceptable and safest way.
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