RV Trip Planning Discussions

Go Back   iRV2 Forums > MOTORHOME FORUMS > MH-General Discussions & Problems
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 02-03-2019, 01:51 PM   #1
Senior Member
 
Carolina Campers
Join Date: Mar 2013
Location: Lumberton ,NC
Posts: 131
Computing Air Pressure for Tires

help me to understand, I weight my coach and the steer axle tires had a weigh of 4320, do I take that number(4320) divide it by 2 and then look for that number(2160) on the tire chart and that is the weight for my steer axle tires?
__________________

danford50 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 02-03-2019, 02:30 PM   #2
Senior Member
 
FlyingDiver's Avatar
 
Newmar Owners Club
Join Date: May 2007
Location: Somewhere....
Posts: 3,972
That's basically it. But to do it right, you need individual wheel (position) weights. If all you have is axle weights, then you'll need to go up at least one weight bracket. Probably two. Because you can't assume the coach is balanced left to right.
__________________

__________________
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 online now   Reply With Quote
Old 02-03-2019, 02:57 PM   #3
Senior Member
 
Tranquil Jim's Avatar
 
Newmar Owners Club
Spartan Chassis
Join Date: Aug 2015
Location: Northwest Washington State or Western Montana, depending on the season.
Posts: 2,271
Quote:
Originally Posted by danford50 View Post
help me to understand, I weight my coach and the steer axle tires had a weigh of 4320, do I take that number(4320) divide it by 2 and then look for that number(2160) on the tire chart and that is the weight for my steer axle tires?
If all you have is the axle weight, I recommend using 55% of the total for each side. Rarely do opposing sides of an axle weigh the same. Using the 55% "fudge factor" provides you a little cushion to cover a possible variance. In your case, 4320 x .55 = 2,378.75 for each corner. Round up to 2,380 for ease of calculation.

Obviously, getting an actual corner weight is the best solution. I have success using state weigh stations that are temporarily closed to do this. They usually leave the scales (and displays) active so truckers can do a self-check. I'm lucky enough to have one about 20 miles away and it is frequently not staffed.

In either case, when you consult the tire manufacturer's tables, be sure you are using the proper one for your tire size. And, if your actual weight falls between two chart weights (as it likely will), round UP to the next chart weight. I also like to add a 5-10 psi cushion, but that's just me.

TJ
__________________
Jim (W7DHC), Diane & Mini Schnauzers, Lizzy & Ellie
2018 Mountain Aire 4047 + 2014 Honda CR-V "toad" w/AF1
Tranquil Jim is offline   Reply With Quote
Old 02-03-2019, 05:05 PM   #4
Senior Member
 
Carolina Campers
Join Date: Mar 2013
Location: Lumberton ,NC
Posts: 131
Quote:
Originally Posted by Tranquil Jim View Post
If all you have is the axle weight, I recommend using 55% of the total for each side. Rarely do opposing sides of an axle weigh the same. Using the 55% "fudge factor" provides you a little cushion to cover a possible variance. In your case, 4320 x .55 = 2,378.75 for each corner. Round up to 2,380 for ease of calculation.

Obviously, getting an actual corner weight is the best solution. I have success using state weigh stations that are temporarily closed to do this. They usually leave the scales (and displays) active so truckers can do a self-check. I'm lucky enough to have one about 20 miles away and it is frequently not staffed.

In either case, when you consult the tire manufacturer's tables, be sure you are using the proper one for your tire size. And, if your actual weight falls between two chart weights (as it likely will), round UP to the next chart weight. I also like to add a 5-10 psi cushion, but that's just me.

TJ
Tj The drive axle weight is 7920 on the rear how would I do it for the dual wheel
danford50 is offline   Reply With Quote
Old 02-03-2019, 05:11 PM   #5
Community Moderator
 
"007"'s Avatar


 
Nor'easters Club
Workhorse Chassis Owner
iRV2 No Limits Club
Join Date: Oct 2004
Posts: 28,902
You will find tire pressures explained here.
__________________
98KSCA, 99MACA, 03 KSCA-3740- 8.1 Chev-- ALLISON Trans
VISIT the NEWMAR QUICK TIPS & EASYMODS 1 & 2
QUICK TIPS # 3
RV SYSTEMS & APPLIANCES & RECALLS --- TECH INFORMATION
"007" is offline   Reply With Quote
Old 02-03-2019, 05:14 PM   #6
Senior Member
 
FlyingDiver's Avatar
 
Newmar Owners Club
Join Date: May 2007
Location: Somewhere....
Posts: 3,972
Quote:
Originally Posted by danford50 View Post
Tj The drive axle weight is 7920 on the rear how would I do it for the dual wheel
Same as for singles except there should be separate lines on your tire inflation chart for duals.
__________________
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 online now   Reply With Quote
Old 02-03-2019, 05:31 PM   #7
Senior Member
 
Norm Mac's Avatar


 
Newmar Owners Club
Freightliner Owners Club
Join Date: Mar 2012
Location: Central Massachusetts
Posts: 739
You have been given some great advice here but I would like to take you in a different direction...
I would be suspicious of the weights you have received.
You did not specify what coach you have but the axle weights seem very low to me.
Even if you have Newmar's lightest coach, a 27' BayStar Sport, the weights you list are still low, if you have a larger coach the numbers are even further off.
According to Newmar, the Unloaded weight of a BayStar Sport 2702 should be approximately 15190.
Your total axle weights (4320 plus 7920) equals 12240.
This is almost 3000 pounds less than the lightest coach Newmar makes when leaving the factory.
I would recommend getting another CatScale weight for this coach unless there is some other factor that I am not aware of.
__________________
Norm & Ellen Proud to be one of the HOOTS
2015 Newmar DutchStar 4369
If I knew retirement was so much fun, I would have done it in my twenties!
Norm Mac is online now   Reply With Quote
Old 02-03-2019, 05:33 PM   #8
Senior Member
 
FlyingDiver's Avatar
 
Newmar Owners Club
Join Date: May 2007
Location: Somewhere....
Posts: 3,972
Quote:
Originally Posted by Norm Mac View Post
You have been given some great advice here but I would like to take you in a different direction...
I would be suspicious of the weights you have received.
You did not specify what coach you have but the axle weights seem very low to me.
I have no idea why he's posting in this forum. His profile says he has a 30' Thor Freedom Elite, which is a smallish Class C. So those numbers are appropriate.
__________________
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 online now   Reply With Quote
Old 02-03-2019, 05:42 PM   #9
Senior Member
 
Tranquil Jim's Avatar
 
Newmar Owners Club
Spartan Chassis
Join Date: Aug 2015
Location: Northwest Washington State or Western Montana, depending on the season.
Posts: 2,271
Quote:
Originally Posted by FlyingDiver View Post
I have no idea why he's posting in this forum. His profile says he has a 30' Thor Freedom Elite, which is a smallish Class C. So those numbers are appropriate.
Because Newmar owners are such good folks?

TJ
__________________
Jim (W7DHC), Diane & Mini Schnauzers, Lizzy & Ellie
2018 Mountain Aire 4047 + 2014 Honda CR-V "toad" w/AF1
Tranquil Jim is offline   Reply With Quote
Old 02-03-2019, 05:49 PM   #10
Senior Member
 
Tranquil Jim's Avatar
 
Newmar Owners Club
Spartan Chassis
Join Date: Aug 2015
Location: Northwest Washington State or Western Montana, depending on the season.
Posts: 2,271
Quote:
Originally Posted by danford50 View Post
Tj The drive axle weight is 7920 on the rear how would I do it for the dual wheel
Divide by 2, then apply the .55 factor. Use the "dual" numbers shown in the chart.

TJ
__________________
Jim (W7DHC), Diane & Mini Schnauzers, Lizzy & Ellie
2018 Mountain Aire 4047 + 2014 Honda CR-V "toad" w/AF1
Tranquil Jim is offline   Reply With Quote
Old 02-03-2019, 05:52 PM   #11
Senior Member
 
Winemaker2's Avatar


 
Join Date: Nov 2006
Location: Western NY
Posts: 2,133
Careful...
Different Tire Mfg charts are set up differently - make sure you use the correct one for your tire mfg

Goodyear - uses Load / tire w/ separate lines for single & dual application

Michelin - uses load / axle end w separate lines for single & dual application

Its a subtle difference but you need to use the charts correctly
__________________
Don & Marge
'13 Newmar Ventana 3433 - '14 CR-V TOAD
'03 Winnebago Adventurer 31Y - SOLD
Winemaker2 is offline   Reply With Quote
Old 02-03-2019, 07:02 PM   #12
Senior Member
 
Tranquil Jim's Avatar
 
Newmar Owners Club
Spartan Chassis
Join Date: Aug 2015
Location: Northwest Washington State or Western Montana, depending on the season.
Posts: 2,271
Quote:
Originally Posted by Winemaker2 View Post
Careful...
Different Tire Mfg charts are set up differently - make sure you use the correct one for your tire mfg

Goodyear - uses Load / tire w/ separate lines for single & dual application

Michelin - uses load / axle end w separate lines for single & dual application

Its a subtle difference but you need to use the charts correctly
Good point, though I'm thinking that the difference is pretty obvious. With one, the load capacity for single and dual is in the same relative ballpark; with the other, the dual rating is close to double the single. Still, I suppose someone unfamiliar with big tires could get confused.

TJ
__________________
Jim (W7DHC), Diane & Mini Schnauzers, Lizzy & Ellie
2018 Mountain Aire 4047 + 2014 Honda CR-V "toad" w/AF1
Tranquil Jim is offline   Reply With Quote
Old 02-04-2019, 06:18 AM   #13
Senior Member
 
Norm Mac's Avatar


 
Newmar Owners Club
Freightliner Owners Club
Join Date: Mar 2012
Location: Central Massachusetts
Posts: 739
Quote:
Originally Posted by FlyingDiver View Post
I have no idea why he's posting in this forum. His profile says he has a 30' Thor Freedom Elite, which is a smallish Class C. So those numbers are appropriate.
Now that makes sense,
I see the discussion has been moved out of the Newmar Forum.
__________________
Norm & Ellen Proud to be one of the HOOTS
2015 Newmar DutchStar 4369
If I knew retirement was so much fun, I would have done it in my twenties!
Norm Mac is online now   Reply With Quote
Old 02-04-2019, 06:32 AM   #14
Senior Member
 
veraken's Avatar


 
Monaco Owners Club
Vintage RV Owners Club
Holiday Rambler Owners Club
Join Date: Jul 2012
Location: Lexington, SC
Posts: 1,227
To determine what the right tire pressure is for you, you need to weigh your MH. Load your MH as you would for travel, fill your gas and water tanks and then get your MH weighed.

If you can't do 4 corner weighing (which would e the best way), this is the procedure to follow:

1. Weigh the coach axles
2. Add 5% to account for possible uneven weight side to side.
3. Divide by the number of tires on each axle.
4. Look to tire chart for your brand to find tire pressure.
5. Add 5 psi for safety
__________________

__________________
Vera & Ken
1998 Holiday Rambler Imperial, RR8S Chassis
Cummins 6C8.3 mechanical engine, 325HP, 3060 Allison
Towing 2014 Ford Explorer
veraken is offline   Reply With Quote
Reply

Tags
air



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
Low oil pressure | erratic oil pressure | inconsistant oil pressure GlennLever Cummins Engines 45 08-28-2014 09:24 AM
Low Power Consumption Computing Devices for MH use Gocoffeer Technology: Internet, TV, Satellite, Cell Phones, etc. 21 11-11-2013 07:31 AM
Air Pressure on Tag vs Tag Tire Air Pressure dmason Monaco Owner's Forum 3 07-24-2013 09:49 AM
Computing in an RV? gcakia Hobbies, Passions & Pastimes 33 05-04-2013 02:07 AM
Air pressure Tires/air bags acoilfld MH-General Discussions & Problems 2 07-09-2012 11:43 AM

» Featured Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 01:57 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.