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 09-18-2011, 06:32 PM   #29
Registered User
 
Vintage RV Owners Club
Gulf Streamers Club
Join Date: Oct 2010
Location: Indiana
Posts: 4,954
The 'thump' test wasnt so much for low air, but bad tires.. Doesnt really apply now-a-days...
__________________

__________________
Midniteoyl 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 09-18-2011, 08:18 PM   #30
RV Mutant #14
 
Wayne M's Avatar


 
Winnebago Owners Club
Texas Boomers Club
Freightliner Owners Club
iRV2 No Limits Club
Join Date: Aug 2008
Location: Texas
Posts: 12,188
Quote:
Originally Posted by randco View Post
You might be right, but on page 3 of the Toyo - RV, Motor home Tire Inflation, Safety & Maintenance - Techinal Bulletin (December 1, 2004) it says and I quote, "All tires lose air at the rate of 1 – 1.5 PSI per month due to natural permeation of the air through the tire’s rubber membrane. Always check the cold inflation pressure of any vehicle that has not been driven for several weeks and re-inflate the tires to the placard pressure before driving.

Tire pressure is affected by the ambient temperature to the extent of approximately 1 PSI per 10 degree (F) change in temperature. As an example, a 20 deg. (F) drop in temperature will result in a 2 PSI drop. A 20 deg. (F) increase in ambient temperature will result in a 2 PSI increase."

Now who am I to argue with the tire manufacturer?
That's why I don't buy Toyo's. I have Michelin, and after two months of parking in a covered (sides open) area, the pressure is at what it was when it was put in storage. Must be tighter molecules in the Michelin, hey?

1Ciderdog, funny you should mention that. I also attend Camp Freightliner and was taught the same thing. Matter of fact, I have the manual from them provided by Goodyear regarding the 2% change. Marvelous minds think alike.
__________________

__________________
Wayne MSGT USMC (Ret) & Earlene (CinCHouse)
2015 Winnebago Tour 42QD
RVM14
It is what it is, and then it is what you make of it.
Wayne M is offline   Reply With Quote
Old 09-19-2011, 05:12 AM   #31
Senior Member
 
randco's Avatar
 
Join Date: Jul 2008
Location: Sarasota, Florida
Posts: 604
Quote:
Originally Posted by Wayne M View Post
That's why I don't buy Toyo's. I have Michelin, and after two months of parking in a covered (sides open) area, the pressure is at what it was when it was put in storage. Must be tighter molecules in the Michelin, hey?

1Ciderdog, funny you should mention that. I also attend Camp Freightliner and was taught the same thing. Matter of fact, I have the manual from them provided by Goodyear regarding the 2% change. Marvelous minds think alike.
Tighter molecules??? I guess that's why Michelin's get those cracks in their sidewalls. Perhaps the molecules are so tight they break and not bend. Now I know why I replaced all six of the Michelin's on my coach with Toyo's. It's all about the molecules.

And I suppose you remember that the ambient temperature was "exactly the same" the day you put it in storage as the day you took it out? Remember, according to you 10 deg. difference at 2% could be significant.

You have Michelin's, why do you use a Goodyear RV Tire Guide?

Doesn't Michelin have anything to say about Ambient Air Temp. & Cold Tire Pressure?
__________________
2004 Damon Escaper 4076
randco is offline   Reply With Quote
Old 09-19-2011, 09:48 AM   #32
Moderator Emeritus
 
RickO's Avatar


 
Join Date: Jan 2007
Location: Litchfield Park, Arizona
Posts: 10,530
Let's keep things friendly here folks. We don't want to get into a "brand war" which is not allowed on this forum.

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

2007 Itasca Ellipse 40FD
RickO is offline   Reply With Quote
Old 09-19-2011, 09:59 AM   #33
RV Mutant #14
 
Wayne M's Avatar


 
Winnebago Owners Club
Texas Boomers Club
Freightliner Owners Club
iRV2 No Limits Club
Join Date: Aug 2008
Location: Texas
Posts: 12,188
Randco,

I'll let you know as soon as i have the time to look around some more.

As previously stated in many posts, the best advice is the advice a person gets from the tire manufacturer.
__________________
Wayne MSGT USMC (Ret) & Earlene (CinCHouse)
2015 Winnebago Tour 42QD
RVM14
It is what it is, and then it is what you make of it.
Wayne M is offline   Reply With Quote
Old 09-19-2011, 01:00 PM   #34
Registered User
 
Vintage RV Owners Club
Gulf Streamers Club
Join Date: Oct 2010
Location: Indiana
Posts: 4,954
Quote:
Originally Posted by Wayne M View Post

As previously stated in many posts, the best advice is the advice a person gets from the tire manufacturer.
It is with the courts too, should that ever be necessary.
__________________
Midniteoyl is offline   Reply With Quote
Old 09-19-2011, 02:33 PM   #35
Senior Member
 
randco's Avatar
 
Join Date: Jul 2008
Location: Sarasota, Florida
Posts: 604
Quote:
Originally Posted by Wayne M View Post
Randco,

I'll let you know as soon as i have the time to look around some more.

As previously stated in many posts, the best advice is the advice a person gets from the tire manufacturer.
As I previously quoted from a tire manufacturer, "Toyo - RV, Motor home Tire Inflation, Safety & Maintenance - Techinal Bulletin (December 1, 2004) page 3, "All tires lose air at the rate of 1 – 1.5 PSI per month due to natural permeation of the air through the tire’s rubber membrane. Always check the cold inflation pressure of any vehicle that has not been driven for several weeks and re-inflate the tires to the placard pressure before driving.

Tire pressure is affected by the ambient temperature to the extent of approximately 1 PSI per 10 degree (F) change in temperature. As an example, a 20 deg. (F) drop in temperature will result in a 2 PSI drop. A 20 deg. (F) increase in ambient temperature will result in a 2 PSI increase."

I guess the tire manufacturers also have a difference of opinion.

I think we both agree that it is prudent to check pressures to make certain the coach can be operated safely. No matter what the conditions.
__________________
2004 Damon Escaper 4076
randco is offline   Reply With Quote
Old 09-19-2011, 04:37 PM   #36
Senior Member
 
randco's Avatar
 
Join Date: Jul 2008
Location: Sarasota, Florida
Posts: 604
Quote:
Originally Posted by RickO View Post
Let's keep things friendly here folks. We don't want to get into a "brand war" which is not allowed on this forum.

Rick
Trying to keep it friendly, just bringing up a few points. There has been a lot of discussion on this forum about Michelin's getting getting sidewall cracks. There have also been numerous discussions about Goodyear's "rivering" problems. I can't speak about the Goodyears because I have never owned them. I have had experience with the Michelin's.
__________________
2004 Damon Escaper 4076
randco is offline   Reply With Quote
Old 09-19-2011, 04:44 PM   #37
Moderator Emeritus
 
RickO's Avatar


 
Join Date: Jan 2007
Location: Litchfield Park, Arizona
Posts: 10,530
No problem. My cautionary post wasn't aimed at anybody in particular but just intended as a reminder.

Thanks,

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

2007 Itasca Ellipse 40FD
RickO is offline   Reply With Quote
Old 09-19-2011, 04:51 PM   #38
Senior Member
 
Elkhartjim's Avatar


 
Newmar Owners Club
Texas Boomers Club
Freightliner Owners Club
Join Date: Jul 2008
Location: Don't mess with Texas
Posts: 3,116
Quote:
Originally Posted by Midniteoyl View Post
The 'thump' test wasnt so much for low air, but bad tires.. Doesn't really apply now-a-days...
Oh no! Jim, are you telling me my air'er up, give'er a thump and let rip theory is hogwash? I guess I'll have to break down and get the four corners weighed, dig out that tire book Mike Cody passed out at Camp Freightliner and pressure the tires to the spec's it calls for.

I'm speaking sarcastically of course. I can't find my whacking stick is really the reason.
__________________
Jim with Judy
2017 Newmar Ventana 4369, 2005 Jeep Wrangler (Rock Crawler), 2016 Jeep Wrangler (Mall Crawler)
Elkhartjim is offline   Reply With Quote
Old 09-19-2011, 05:15 PM   #39
RV Mutant #14
 
Wayne M's Avatar


 
Winnebago Owners Club
Texas Boomers Club
Freightliner Owners Club
iRV2 No Limits Club
Join Date: Aug 2008
Location: Texas
Posts: 12,188
Judy has the whackin' stick! You should know that!

Now teach her that it is the tires she is supposed to be whackin'

Better yet, maybe she does have it right. (hee hee)
__________________
Wayne MSGT USMC (Ret) & Earlene (CinCHouse)
2015 Winnebago Tour 42QD
RVM14
It is what it is, and then it is what you make of it.
Wayne M is offline   Reply With Quote
Old 09-19-2011, 08:36 PM   #40
Senior Member
 
mikron's Avatar
 
Thor Owners Club
Ford Super Duty Owner
Join Date: Aug 2010
Posts: 860
Our 22.5 tires on our Windsport F53 22,000 chassis coach after weighing front and back axles at a Pilot CAT scale 20,800 lbs and based on the Michelin chart 80 lbs all around.
__________________
Mike, Janet & Duchess (cavalier King Charles)
2008 35B windsport, Brazel's rear TracBar, Koni shocks & Safe T plus steering
mikron is offline   Reply With Quote
Old 09-20-2011, 10:24 PM   #41
Registered User
 
Vintage RV Owners Club
Gulf Streamers Club
Join Date: Oct 2010
Location: Indiana
Posts: 4,954
What was the weights per axle.. that what you need..
__________________
Midniteoyl is offline   Reply With Quote
Old 09-23-2011, 10:17 AM   #42
Senior Member
 
Lincolnboy2's Avatar


 
Texas Boomers Club
Fleetwood Owners Club
Solo Rvers Club
Ford Super Duty Owner
Join Date: Jul 2011
Location: Grand Prairie, TX (DFW)
Posts: 3,536
Quote:
Originally Posted by Wayne M View Post
Aw heck!
Okay, I'm just going to assume some information.

Just for the sake of explanation, let us assume that the tires are Goodyear 225/70R19.5, okay?

Lets start out with a simple chart.

For single tires per axle

PSI---------------70-------75-------80------85------90-------95---------100 (There's more but let's stop there)
Weight(S)------2895-----3040----3195---3315---3450---3640(F)-----3715 (F = Load range F)

Now, let us assume that the weight on your tire is 3040 per tire on a single axle (The psi setting has to be the same for all tires on the same axle)

So, let us assume that you inflate your tires to 75 psi. I mean, after all you just came back from the CAT scale and you know what your weight is. You drive home pick up the wife, 50 pound dog. The dog sits at DW's feet. Total weight is an additional 150 pounds on the passenger tire. (You didn't think I was going to make your DW heavy, did you?) You are 150 pounds overweight on the passenger tire. Even if you had distributed the weight evenly across the axle, you would still be 75 pounds per tire overweight. If you experienced a drop in temperature or altitude, you would be additionally overweight. (Remember, this is just an example - I actually like working with the 22.5 inch tires)

So do the fudge factor:

Inflate the tires to 80 psi, and the tires are now rated for 3195 pounds. Now you have a fudge factor of 155 additional pounds per tire, or a total of 310 pounds you can put in the RV distributed across the axle. See where this is going. No? Okay, now stop at Wall-world for the night, go in, buy some groceries, supplies, whatever, and make sure you go to the bathroom scale and weigh all that stuff, because you are not overweight on the tires. Don't forget that DW and Fido are using up 150 pounds of that, so you only have a margin of 160 pounds. Don't go to Mcdonald's every night and eat hamburgers. Don't fret - more fudge coming.

Inflate the tires to 85 psi, and the tires are now rated for 3315 pounds per tire. That is 275 pounds per tire, or 550 pounds across the axle. DW and Fido can be comfortably safe and do not have to have salad every night.

Now let us say that you are running at 85 psi, and when you checked the tires at that pressure the ambient temperature was 90 degrees (I'm in Texas). You are at sea level. You head North. The temperature drops to 60 degrees. That represents a 6% decrease in pressure. 85 minus 6% equals a 5.1 psi change, and the gauge will only show a 5 psi change. So you are at 80 psi the next morning when you get up. Oops, wait a minute, you gained 2000 feet in altitude. That is a 0.96 psi increase in pressure, so your actual tire pressure reading should be 81 psi. Look at the chart. Are you still within range of the tire manufacturers recommendations? Do you need to change the tire pressure by adding more air? Nope. Smile, be on your way. If you go to the other extremes, like from 90 degrees to 120 degrees you are going to gain 5 psi which will put you at 90 psi plus one for altitude of 0.96 psi so you are at 91 psi. That particular tire in this example goes to 110 psi at a max load of 3970(G Rated tire). Are you still within the parameters. Most definitely.

You can do the math for the duals, and remember their load rating for this specific tire is 3115 per tire. That is a total axle load rating of 12, 460 pounds. Your front steer tires, single tire on each end of a single axle at 85 psi is 6630 pounds.

I cannot express this enough. Never let air out of a hot tire that has not set for several hours and come to ambient temperature. The best time to check a tire is early in the morning. If the sun is hitting the outer dual, it will normally be at a higher psi than the inside dual. If both are on the shady side, the inside dual may be a tad higher that the outside dual, because the inside dual is getting heat from the RV. After about a mile down the highway they will both catch up with each other.

When to check tire pressure:
  • Before each trip
  • Every morning during long trips
  • Before you leave and when you return home on short trips
  • Before and after storing your vehicle
  • AT least once per month while the vehicle is in storage
The only way to know what the proper inflation for your tires are to weigh the vehicle, preferably at each corner, and use the manufacturer's tire inflation chart.

Happy trails. If I made a mistake in the computations, well, I'm not a tire engineer nor a math major.

Edited: Here is a link to the Goodyear Tire Inflation Loading web site.
Once there click on the blue "Download RV Tire & Care Guide."
Lots of great information. Thanks for the info!
__________________

__________________
Kent - '03 Fleetwood Storm Ford F-53 V-10
With Susie (Lhasa); Angie (Shorkie) Ferbie (ShihTzu)
In Memoriam: Katie, Spencer and Zoey
Lincolnboy2 is offline   Reply With Quote
Reply



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
Help with Tire Pressure Cathy&Paula Newmar Owner's Forum 10 05-19-2010 10:29 PM
A couple of tire pressure questions JayGee Workhorse and Chevrolet Chassis Motorhome Forum 13 04-27-2010 09:16 PM
Correct Tire Pressure VACMAN Newmar Owner's Forum 28 10-01-2009 07:54 AM
Correct tire pressure? tps0424 National RV Owner's Forum 13 09-25-2009 02:45 PM
Tire Pressure Johnhdj MH-General Discussions & Problems 3 04-07-2005 03:54 PM

» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 07:14 AM.


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