Free 7 Day Trial RV GPS App RV Trip Planner Campground Reviews RV Maintenance Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > THE OWNER'S CORNER FORUMS > Newmar Owner's Forum
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 01-15-2014, 10:17 AM   #1
Member
 
Join Date: Sep 2013
Location: Stuart Florida
Posts: 60
Inflating RV Tires

Vehicle is a 2007 40' Dutch Star. 400 Cummins. I have tried to inflate the front tires to the 120 psi advised and find that the onboard compressor does not seem to put out that volume when I connect to the air chuck. I have to carry a separate pancake compressor that will do the job. Is there any way to increase the air out put on the coach or is there a secret to achieving the objective that I haven't learned yet. Suggestions welcome.
Thanks
THERAPY GUY is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 01-15-2014, 10:30 AM   #2
Senior Member
 
Skip426's Avatar


 
Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 24,262
The 120 PSI , would be an MAX inflation, do you have your axle weights?
Most times MAX is not required for the weight of the axle.
If you get the scale weight of the MH loaded for travel, and inflation chart from the tire manufacturers web site. I think you will find that the MAX is not required, and in many cases results in poor handling.
The engine mounted compressor , will have a tough time with inflation over 100 PSI , and there are several post on the type of compressors other members carry.
__________________
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Skip426 is offline   Reply With Quote
Old 01-15-2014, 11:19 AM   #3
Member
 
Texas Boomers Club
Forest River Owners Club
Freightliner Owners Club
Join Date: Sep 2013
Location: Dallas, TX
Posts: 36
Guy...I don't know of anyone that runs max air pressure in their MH tires...it's usually much less. As mentioned, handling and ride will be horrible with 120lbs in the tires.

Go to a truck stop with scales (Love's, etc) and have them weigh the coach for you. With the axel weight you can then refer to the pressure chart from your tire manufacturer to get the proper amount of air.

The max psi in my tires is 110lbs and I run mine at 85-90 psi per the chart for my tires and MH weight.

Terry
__________________
2015 Forest River, Berkshire 38RB
Freightliner Chassis
2007 Jeep Wrangler Unlimited
tkdavis is offline   Reply With Quote
Old 01-15-2014, 11:27 AM   #4
Moderator Emeritus
 
RickO's Avatar


 
Join Date: Jan 2007
Location: Litchfield Park, Arizona
Posts: 10,530
Yep, as pointed out, on board compressors really struggle over 100 lbs PSI. They'll eventually get a tire a bit over that but it can take forever so many carry dedicated compressors to handle tire inflation.

Also as pointed out... it's highly unlikely that your tires need to be inflated to 120 lbs.

Rick
__________________
Rick, Nancy, Peanut & Lola our Westie Dogs & Bailey the Sheltie.

2007 Itasca Ellipse 40FD
RickO is offline   Reply With Quote
Old 01-15-2014, 11:42 AM   #5
Senior Member
 
dennis45's Avatar
 
Join Date: Jun 2012
Location: AB
Posts: 7,587
Here are a couple of videos that show how to inflate RV Tires off the on board compressor. I have this arrangement and find it works OK. I little slower than a Pancake but gets the job done and does not take up space in my basement.


http://m.youtube.com/user/RVgeeks?de...user%2FRVgeeks
__________________
2019 Unity LTV CB, pushed by a 2013 Honda CRV, BlueOx Baseplate, Aventa Bar & Patriot Brake
dennis45 is offline   Reply With Quote
Old 01-15-2014, 08:58 PM   #6
Senior Member
 
Join Date: Jan 2011
Posts: 516
You need to at least know your front axle weight. Preferably corner weight. On my 2006 Mountain Aire I run 95 lbs in the front tires.
__________________
2006 Mountain Aire, Jeep LJ, 900 watts of solar, boondocking life away! Volunteer Fire Fighter!
hes4all is offline   Reply With Quote
Old 01-15-2014, 09:02 PM   #7
Senior Member
 
Mr_D's Avatar
 
Country Coach Owners Club
Solo Rvers Club
iRV2 No Limits Club
Join Date: May 2011
Location: Vancouver, WA
Posts: 37,636
Quote:
Originally Posted by Skip426 View Post
The 120 PSI , would be an MAX inflation, do you have your axle weights?
Most times MAX is not required for the weight of the axle.
If you get the scale weight of the MH loaded for travel, and inflation chart from the tire manufacturers web site. I think you will find that the MAX is not required, and in many cases results in poor handling.
The engine mounted compressor , will have a tough time with inflation over 100 PSI , and there are several post on the type of compressors other members carry.
ON TRUCK size tires the cold pressure on the sidewall is the MINIMUM required to support the maximum weight rating of the tires. Same with the tire charts, it's the MINIMUM cold pressure to support the weight.

From page 2 of the 06/07 Michelin RV Tire Guide:
Quote:
"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 the Firestone/Bridgestone RV tire guide:
Quote:
Bear in mind that these are maximum ratings. The sidewall of the tire shows maximum load and minimum inflation pressure for that load
From the GoodYear RV Tire Guide:
Quote:
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
Quote:
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!!
__________________
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft, HWH Active Air
Charter Good Sam Lifetime Member, FMCA, SKP
RV'ing since 1957, NRA Benefactor Life, towing '21 Jeep JLU Rubicon Ecodiesel
Mr_D is offline   Reply With Quote
Old 01-15-2014, 09:10 PM   #8
Senior Member
 
Mr_D's Avatar
 
Country Coach Owners Club
Solo Rvers Club
iRV2 No Limits Club
Join Date: May 2011
Location: Vancouver, WA
Posts: 37,636
Quote:
Originally Posted by tkdavis View Post
Guy...I don't know of anyone that runs max air pressure in their MH tires...it's usually much less. As mentioned, handling and ride will be horrible with 120lbs in the tires.

Go to a truck stop with scales (Love's, etc) and have them weigh the coach for you. With the axel weight you can then refer to the pressure chart from your tire manufacturer to get the proper amount of air.

The max psi in my tires is 110lbs and I run mine at 85-90 psi per the chart for my tires and MH weight.

Terry
Our DSDP came with a 12,000# front axle and 275/70 22.5's According to the charts I needed 125 psi in the front Michelins. Newmar had Spartan replace the front axle with a 14,600# unit. At the same time they replaced the front wheels but not the tires. Then the gave me a letter on Michelin letterhead allowing the tires to be rated at the 125 psi rating with 120 psi in them as that was the max even the heavy duty rims would take. Ran them that way for 6 years or so with no problems. Have now replaced the front tires with 305/70's on Alcoa wheels.

And again, the pressure on the sidewall of a truck size tire is NOT the maximum that tire should ever have, it is the minimum to support the maximum rating of that tire.
__________________
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft, HWH Active Air
Charter Good Sam Lifetime Member, FMCA, SKP
RV'ing since 1957, NRA Benefactor Life, towing '21 Jeep JLU Rubicon Ecodiesel
Mr_D is offline   Reply With Quote
Old 01-15-2014, 09:11 PM   #9
Senior Member
 
JFXG's Avatar
 
Newmar Owners Club
Freightliner Owners Club
Join Date: May 2012
Location: Today? Canterbury, CT
Posts: 4,765
Your '07 will be a few thousand lbs heavier than my '02, and that difference will mostly be in the front axle. I have 19K rear axle and 12K front; you have 20K rear and (I think) 14.2K or 14.4K front. You'll probably need about 110-115lbs in the front (depending on tire size) and about 90-95lbs rear. Get weighed and set the proper pressure.

You'll have a hard time getting 110lbs into the fronts with the onboard compressor, and even 90lbs in the rears will be a slow pita. Onboard compressor relieves at 120psi, and cuts in again at 90psi. I tap danced with the onboard compressor for a year, and finally bit the bullet and bought a 150psi compressor from HF ($100 on sale). It lives in the small bay just forward of my batteries, and comes in handy for other things, too.

JG
__________________
John, Diane, and Lincoln, the guard cat. RVM103
Fulltimers since June 2012
2002 Dutch Star 40, Freightliner, Cat 3126,
2004 Element
JFXG is offline   Reply With Quote
Old 01-16-2014, 06:43 AM   #10
Member
 
vonkamp's Avatar
 
Newmar Owners Club
Coastal Campers
Spartan Chassis
Join Date: Nov 2013
Posts: 70
If you have one of those cheap plastic coiled hoses, I would throw it out and get a nice 3/8 or 1/2 dia. 50' rubber compressor hose. The big box stores should sell them. The extra volume will move more air quicker...
Cheers,
Baron
vonkamp is offline   Reply With Quote
Old 01-16-2014, 08:16 AM   #11
Senior Member
 
Tireman9's Avatar
Commercial Member
 
Join Date: Mar 2010
Location: Akron, Ohio
Posts: 2,417
Quote:
Originally Posted by Mr_D View Post

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

I can't find the TOYO document you are quoting.
__________________
Retired Design & Quality Tire Eng. 40+ years experience. You can listen to self appointed "Know it all" or someone that actually designed tires and has performed thousands of failed tire "autopsies".
Tireman9 is offline   Reply With Quote
Old 01-16-2014, 08:18 AM   #12
Senior Member
 
Tireman9's Avatar
Commercial Member
 
Join Date: Mar 2010
Location: Akron, Ohio
Posts: 2,417
Quote:
Originally Posted by THERAPY GUY View Post
Vehicle is a 2007 40' Dutch Star. 400 Cummins. I have tried to inflate the front tires to the 120 psi advised and find that the onboard compressor does not seem to put out that volume when I connect to the air chuck. I have to carry a separate pancake compressor that will do the job. Is there any way to increase the air out put on the coach or is there a secret to achieving the objective that I haven't learned yet. Suggestions welcome.
Thanks
Where did you get the instruction to inflate your fronts to 120 psi?

Is that the inflation shown on the tire Placard? or are you just reading the information on the tire about the Max cold pressure?
__________________
Retired Design & Quality Tire Eng. 40+ years experience. You can listen to self appointed "Know it all" or someone that actually designed tires and has performed thousands of failed tire "autopsies".
Tireman9 is offline   Reply With Quote
Old 01-16-2014, 09:06 AM   #13
Senior Member
 
Sky_Boss's Avatar
 
Newmar Owners Club
Freightliner Owners Club
Spartan Chassis
Join Date: Apr 2012
Location: ON THE ROAD...SOMEWHERE
Posts: 6,958
Actually, regarding onboard compressor...if I understood my Spartan Owner training, you can increase the traditional 120 PSI pressure in the tanks by adjusting the governor. I am verifying this and will get back to you on that.

FWIW, my front wheels need a minimum of about 112 PSI when running at the rated 14,600# axle rating. For some that means after adding 5 PSI for safety I am at 117 PSI. That would be a bit of a challenge for the on board set at 120 PSI.

To be honest I have never used my onboard system and judging from the condition of the chuck, neither did the previous owners. My 150 PSI Sears compressor meets my needs. It is a bit noisier than I like but running the engine isn't that much better.

A good chuck with a clip to hold the chuck on the valve stem, built in pressure gauge, with both and air up and air dump system is the way to go. Keeps the knees and back happy too.

POWERTANK - CO2 Air Systems
__________________
Don, Sandee & GSD Zeus. Guardian GSDs Gunny (7/11/15) & Thor (5/5/15)
2006 2015 DSDP 4320 4369, FL Chassis, 2013 CR-V 2020 Jeep Overland, Blue Ox Avail, SMI AF1.
[SIGPIC][/SIGPIC]
Sky_Boss is offline   Reply With Quote
Old 01-16-2014, 12:28 PM   #14
Senior Member
 
Sky_Boss's Avatar
 
Newmar Owners Club
Freightliner Owners Club
Spartan Chassis
Join Date: Apr 2012
Location: ON THE ROAD...SOMEWHERE
Posts: 6,958
From Mike O'niel @ Spartan

Yes the governor is adjustable. Setting it to 130 psi cutout is where we set the governor on current production. When you change the cut out pressure it also changes the cut in. The governor has about 25 psi differential between cut out and cut in built into it. This does not mean you will get more pressure into your tires. The volume of the compressor will not overcome the volume in the tires by setting the pressure higher. You will get approximately 95 psi and maybe 100 psi to the tires. This will get enough air into the tires to safely drive to a high volume air source.

Your governor setting at 120psi cut out will give you a cut in at approximately 95 psi. The cut out at 130psi will bring the cut in to 105 psi.
__________________
Don, Sandee & GSD Zeus. Guardian GSDs Gunny (7/11/15) & Thor (5/5/15)
2006 2015 DSDP 4320 4369, FL Chassis, 2013 CR-V 2020 Jeep Overland, Blue Ox Avail, SMI AF1.
[SIGPIC][/SIGPIC]
Sky_Boss is offline   Reply With Quote
Reply

Tags
tires



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
New Tires for MH MelnDee Class A Motorhome Discussions 17 08-14-2013 07:44 PM
New Tires 275/70R 22.5 adonh Class A Motorhome Discussions 10 07-09-2013 03:19 PM
Retread Tires adonh Class A Motorhome Discussions 12 06-23-2013 12:48 PM
Need quality Travel Trailer tires?? bubbajean Travel Trailer Discussion 11 06-13-2013 10:14 PM

» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 12:05 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.