Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
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 03-26-2014, 01:16 PM   #1
Member
 
Join Date: Nov 2013
Posts: 53
Tire pressures

Please excuse my ignorance, but as a newbie I would like to know if any motorhome owners out there inflate their tires the same psi all the way around using the tire manufactures max. rating or just under depending on weight. It seems hard for me to believe that the majority of class A owners drive up onto scales a weigh each wheel and inflate accordingly. There has to be rv'ers out there that have had good results with standard air pressures all the way around. Any comments or experiences would be greatly appreciated. Thanks in advance , Bruc .
__________________

__________________
bruc 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 03-26-2014, 01:38 PM   #2
Senior Member
 
FlyingDiver's Avatar
 
Newmar Owners Club
Join Date: May 2007
Location: Somewhere....
Posts: 3,820
Quote:
Originally Posted by bruc View Post
Please excuse my ignorance, but as a newbie I would like to know if any motorhome owners out there inflate their tires the same psi all the way around using the tire manufactures max. rating or just under depending on weight. It seems hard for me to believe that the majority of class A owners drive up onto scales a weigh each wheel and inflate accordingly. There has to be rv'ers out there that have had good results with standard air pressures all the way around. Any comments or experiences would be greatly appreciated. Thanks in advance , Bruc .
Never a good idea to use "standard" weights or pressures. Getting weights done once is not that hard to do, and it's not likely to change all that much over time.
__________________

__________________
2008 King Aire 4562, Spartan K3(GT) w/ Cummins ISX 600
2014 Jeep Grand Cherokee Overland 5.7L V8 Hemi w/ Blue Ox Aventa LX Tow Bar and baseplate, SMI Air Force One brake
FlyingDiver is offline   Reply With Quote
Old 03-26-2014, 01:51 PM   #3
Senior Member
 
seasonedsole's Avatar
 
Mid Atlantic Campers
Ford Super Duty Owner
Join Date: Sep 2010
Location: NE PA
Posts: 154
There are a lot of ill handling motorhomes out there because of inflating to max on the sidewall. I someone doesn't want to get it weighed, or hasn't been able to, they should inflate to recommended pressure on the sticker by the driver. Good luck, be safe.
__________________
Doug and Lisa, FMCA 436113
2006 Fleetwood Providence 39L
350 HP Cat, Spartan, 24' ATC enclosed
Subaru Outback, Cricket SW3
seasonedsole is offline   Reply With Quote
Old 03-26-2014, 02:12 PM   #4
Senior Member
 
JFXG's Avatar
 
Newmar Owners Club
Freightliner Owners Club
Join Date: May 2012
Location: Today? Mercer, PA
Posts: 3,615
Quote:
Originally Posted by bruc View Post
....would like to know if any motorhome owners out there inflate their tires the same psi all the way around using the tire manufactures max. rating or just under depending on weight. It seems hard for me to believe that the majority of class A owners drive up onto scales a weigh each wheel and inflate accordingly. There has to be rv'ers out there that have had good results with standard air pressures all the way around. Any comments or experiences would be greatly appreciated. Thanks in advance , Bruc .
Hi, and Welcome! Do not apologize, as everyone starts knowing nothing. The only stupid question is the one unasked.

The fact is that motorhomes are different from cars. There is no standard pressure. I remember back in the '60s when virtually all cars had the same size tires, and it was simple gospel that you inflate car tires to 28 lbs. Those days are gone forever.

Most motorhomes (and their tires), particularly those that fulltime, live their whole life at or near max gross weight. This means the tires are constantly stressed, making proper inflation all the more important, and under-inflation all the more dangerous.

You could inflate all to the max and know you're safely inflated, but you'd likely then have to suffer a much stiffer and harsher ride than necessary. But you don't need to be constantly weighing your coach, either.

The fact is when heavily loaded, tires are very pressure sensitive-- mostly to underinflation. The first step is to get weighed, four corners if possible. Then you inflate all tires on a particular axle to the proper pressure for the heaviest side of that axle. Its important for handling that each axle be balanced laterally. Example: your front left weighs 5000 lbs, front right weighs 5300 lbs. Inflate both front tires to the proper pressure for a 5300 lb load, according to the inflation tables provided by your tire manufacturer. Your left rear weighs 10100lbs, your right rear 9400lbs. Inflate all four tires on that axle to the recommended pressure for 10100lbs, again according to the inflation table.

If all you can get is the basic axle weights, just cut that weight in half and use that number. That will work ok, but you're better off with the four individual weights.

Once you've been properly weighed, there's no need to weigh again soon unless you shift a lot of weight around or add (or remove) a lot of weight to the coach. Since we tend to accumulate "stuff" in the coach without realizing it, its probably a good idea to reweigh annually.

I'm sure there are some folks who just pump in some arbitrary air pressure and go blithely about their business, but their continued good health and fortune is more a matter of happenstance than prudent operation, and its a testament to the quality of modern tire design. As their tires age their risk will elevate exponentially regarding tread wear, internal structural failure, and handling reliability.

Good Luck!!
__________________
John & Diane, Fulltimers. RVM103 NHSO
On the road since June '12 with Lincoln, the guard cat.
2002 Dutch Star 40, Freightliner, Cat 3126, 2004 Element
JFXG is offline   Reply With Quote
Old 03-26-2014, 03:05 PM   #5
Senior Member
 
Ford Super Duty Owner
Join Date: Feb 2011
Posts: 135
The tire inflation number is the minimum air for the maximum load. I have always used this number with no obvious handling issues. My tires are the original tires to the coach which was built in Nov of 1999. I just got home yesterday from a 3000 mile trip with no issues. Heat is the number one killer of tires and reduced air pressure is one of the main causes of heat.
__________________
Peterd503 is offline   Reply With Quote
Old 03-26-2014, 03:21 PM   #6
Senior Member
 
gruelens's Avatar
 
Join Date: Jul 2012
Posts: 1,289
Quote:
Originally Posted by Peterd503 View Post
The tire inflation number is the minimum air for the maximum load. I have always used this number with no obvious handling issues. My tires are the original tires to the coach which was built in Nov of 1999. I just got home yesterday from a 3000 mile trip with no issues. Heat is the number one killer of tires and reduced air pressure is one of the main causes of heat.
It is my hope that we are not advocating, to forum members, driving RVs on 15+ year old tires. Too many aged out tires have come apart causing structural damage and accidents.
__________________
George R. - Fulltiming since January '03
2007 Newmar Mountain Aire 3991
2012 Chevy Malibu LT1
gruelens is offline   Reply With Quote
Old 03-26-2014, 08:07 PM   #7
Senior Member
 
Tobias7000's Avatar


 
Country Coach Owners Club
Newmar Owners Club
Freightliner Owners Club
Join Date: Apr 2013
Location: Portland
Posts: 278
Why doe Les Schwab inflate to max?

Had my tires changed recently and Les Schwabb inflated to what the manufacturers plate listed (on the wall left of my drivers seat). My owners manual stresses that I should never run the tires at any other pressure than what the plate lists. I don't know for sure, but I understand the recommended pressure is there by law. So this process of measuring and adjust pressure is news to me (I am new to the motor coach life). Why wouldn't my owners manual discuss this? I am eager for more insight as well and thank the questioner for posting this.
__________________
Tobias7000 is offline   Reply With Quote
Old 03-26-2014, 08:13 PM   #8
Senior Member
 
FlyingDiver's Avatar
 
Newmar Owners Club
Join Date: May 2007
Location: Somewhere....
Posts: 3,820
Quote:
Originally Posted by Tobias7000 View Post
Had my tires changed recently and Les Schwabb inflated to what the manufacturers plate listed (on the wall left of my drivers seat). My owners manual stresses that I should never run the tires at any other pressure than what the plate lists. I don't know for sure, but I understand the recommended pressure is there by law. So this process of measuring and adjust pressure is news to me (I am new to the motor coach life). Why wouldn't my owners manual discuss this? I am eager for more insight as well and thank the questioner for posting this.
The pressures on the plate are for the original tires at the maximum loaded weight of the coach as specified by the builder. If the tires have changed (different manufacturer, different size, load range, etc), or if you're not running at max weight, then the plate numbers are not correct. The tire manufacturer will have a chart specifying what pressure you should have in those specific tires for the weight actually on the tire.

I'm sure that there is a law requiring a recommended pressure. That doesn't mean that the recommended pressure is correct in all (or even most) situations.

I also really doubt the owner's manual says exactly what you think it says. Can you quote the exact passage?
__________________
2008 King Aire 4562, Spartan K3(GT) w/ Cummins ISX 600
2014 Jeep Grand Cherokee Overland 5.7L V8 Hemi w/ Blue Ox Aventa LX Tow Bar and baseplate, SMI Air Force One brake
FlyingDiver is offline   Reply With Quote
Old 03-26-2014, 08:49 PM   #9
Senior Member
 
Ray,IN's Avatar
 
Join Date: Aug 2001
Location: North America somewhere
Posts: 13,709
The RMA-Rubber Manufacturers Association states that over 90% of all tire failures are due to underinflation/overloading. It is better to err on the side of higher pressure.
__________________
2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member,FMCA."We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert the Constitution. "Abraham Lincoln"
Ray,IN is offline   Reply With Quote
Old 03-26-2014, 08:59 PM   #10
Senior Member
 
FlyingDiver's Avatar
 
Newmar Owners Club
Join Date: May 2007
Location: Somewhere....
Posts: 3,820
True, but over-inflating reduces braking effectiveness and negatively impacts handling.

Getting it right by the tire manufacturer charts is the best policy.
__________________
2008 King Aire 4562, Spartan K3(GT) w/ Cummins ISX 600
2014 Jeep Grand Cherokee Overland 5.7L V8 Hemi w/ Blue Ox Aventa LX Tow Bar and baseplate, SMI Air Force One brake
FlyingDiver is offline   Reply With Quote
Old 03-27-2014, 12:39 AM   #11
Senior Member
 
Tobias7000's Avatar


 
Country Coach Owners Club
Newmar Owners Club
Freightliner Owners Club
Join Date: Apr 2013
Location: Portland
Posts: 278
Quote:
Originally Posted by FlyingDiver View Post
Can you quote the exact passage?
There are about six pages on tire pressure and safety. Here are a few paragraphs from the CC Inspire 360 (2008) owners manual.

"Tire Industry Changes
The tire industry, as a whole, has changed its traditional stance on adjusting cold tire inflation pressure for RV tires installed on recreational vehicles and busses. Previously, tire manufacturers supported a policy where tire inflation could be adjusted according to the actual loaded weight of the vehicle. Now, the major tire manufacturers recommend that medium duty truck tires be maintained at the pressure that corresponds to the Gross Axle Weight Rating for the axle to which they are mounted. To make this recommendation uniform across the industry, tire manufacturers strongly urge the consumer to keep all tires inflated to the pressures recorded on the Federal Tire Label.

Federal Tire Label Information
The motor home's important tire information is contained on the Federal Tire Label (Figure 1.8, page 1.19), which is located on the transmission shift panel near the driver's left knee. This label includes recommended tire size, wheel size, and cold tire inflation pressure for each tire position on the motorcoach. "

From another page...
Country Coach Tire Inflation Policy
" Federal law requires that the tire's maximum load rating be molded into the sidewall of the tire. If you look there, you can see the maximum load allowed and the cold air inflation pressure required to carry that stated maximum load. Less air pressure restricts the tire to carry a lighter load. For your safety, always adhere to the Federal Tire Label for proper inflation numbers. "

This has been a good thread. Thanks everyone!
__________________
2015 Newmar Dutch Star 4366 pulling a 2014 Dodge Ram Truck
Tobias7000 is offline   Reply With Quote
Old 03-27-2014, 01:03 AM   #12
Senior Member
 
Tobias7000's Avatar


 
Country Coach Owners Club
Newmar Owners Club
Freightliner Owners Club
Join Date: Apr 2013
Location: Portland
Posts: 278
Another interesting paragraph from the manual.

"Country Coach recommends that the cold tire inflation pressures should at all times be maintained at the inflation pressure(s) recorded on the Federal Tire Label. There are no acceptable circumstances where tire inflation pressure(s) should be reduced below that pressure recorded on the Federal Tire Label. "
__________________
2015 Newmar Dutch Star 4366 pulling a 2014 Dodge Ram Truck
Tobias7000 is offline   Reply With Quote
Old 03-27-2014, 01:26 AM   #13
Senior Member
 
UFO Pilot's Avatar
 
Winnebago Owners Club
Workhorse Chassis Owner
Join Date: Aug 2007
Location: Sonoma County, CA
Posts: 4,612
Winnebago said my tires should be inflated to 105 pounds. The service shop inflated them to 110 per the max on the sidewalls. I had the Coach weighed and the manufacturers tables said I should run 85. I choose to run 95 for a safety factor. The 15 pounds less I am now running sure improved the ride. I also use the Tire-SafeGuard for constant monitoring.
__________________
Wayne & Roberta and Maggie the Miracle Dog
08 Winnebago Destination 39W Gas UFO Workhorse Chassis
Making the Journey in our Destination

UFO Pilot is online now   Reply With Quote
Old 03-27-2014, 08:43 AM   #14
Senior Member
 
Triker56's Avatar
 
Fleetwood Owners Club
Join Date: Jun 2009
Posts: 3,948
Quote:
Originally Posted by Peterd503 View Post
My tires are the original tires to the coach which was built in Nov of 1999. I just got home yesterday from a 3000 mile trip with no issues.
What make are those tires? Hard to believe if they are OEM Michelin's XRV's that old and the sidewalls are still good and not dry rotted.
If they are you should be buying some lotto tickets.

Some owners would have have replaced them 2-3 times by now and spent around 6-9K doing it.

On my Aug 98 built 99 I now have almost 9 years on the first replacement(May 2005) G670's put on. Plan on a 2015 replace with them.

For the OP have your RV weighed and use the manufacture of your tires PSI table for weight. Very seldom that the front & rear will take the same PSI.

How to weigh your RV 2MB PDF
__________________

__________________
99 Discovery 34Q ISB
2014 MKS AWD EcoBoost Toad
Fulltime Since "99"
Triker56 is offline   Reply With Quote
Reply

Tags
tire pressure



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
2014 Essex Tire Pressures slabman Newmar Owner's Forum 6 03-18-2014 09:09 AM
WOW-Check your tire pressures! Lincolnboy2 Class A Motorhome Discussions 84 02-20-2014 05:58 PM
Tire pressures? Recommended seems very low. plasma800 Class A Motorhome Discussions 22 01-24-2014 10:27 AM
Checking MH tire pressures with/without removing wheel covers? mikecosgrove Forest River Owners Forum 3 01-22-2014 01:01 PM
Tire pressures? Mike Jorgeson Workhorse and Chevrolet Chassis Motorhome Forum 8 11-23-2013 09:54 PM

» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 12:03 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.