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 09-05-2013, 10:31 AM   #1
Member
 
Monaco Owners Club
Join Date: May 2012
Location: Louisville, KY @ the moment
Posts: 37
Question Front -v- Rear tire press?

Will I typically have higher pressures in the rear dual drivers vs front steer tires?
I know this simple tire pressure thing has been discussed at length but the more I read the more confused... well let's just say there remains an element of uncertainty for me and I may have had things bass-ackwords.

2 axle DP
Goodyear G670 RV
255/70R22.5

I realize I need actual weights but for simplified discussion:
assume a GVW of 25,500 lb
assume equal weight distribution over 6 tires:
25,500 / 6 = 4,250lb each tire.

So... I'd inflate the front steering tires to 82 PSI. + a bit more for grandmother <grin>
And... the rear dual driving tires to 90 PSI. + ""

?Correct?

From Goodyear info I interpolated to one PSI below:
Single Dual PSI
4190 3970 80
4226 3971 81
4262 3972 82 front tires
4298 3973 83
4334 3974 84
4370 3975 85
4406 4035 86
4442 4095 87
4478 4155 88
4514 4215 89
4550 4275 90 rear tires
4575 4302 91
4600 4329 92
4625 4356 93
4650 4383 94
4675 4410 95

Regards,
Tom C.
__________________

__________________
Tom&Mel with a new Red Wrangler Unlimited toad & a 2005 Monaco Cayman 36PDQ to tow the toad.
Tomthepilot 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 09-05-2013, 11:10 AM   #2
Senior Member
 
Steve Ownby's Avatar
 
Join Date: Nov 2008
Location: Cosby, Tn
Posts: 6,399
Quote:
Originally Posted by Tomthepilot View Post
Will I typically have higher pressures in the rear dual drivers vs front steer tires?
I know this simple tire pressure thing has been discussed at length but the more I read the more confused... well let's just say there remains an element of uncertainty for me and I may have had things bass-ackwords.

2 axle DP
Goodyear G670 RV
255/70R22.5

I realize I need actual weights but for simplified discussion:
assume a GVW of 25,500 lb
assume equal weight distribution over 6 tires:
25,500 / 6 = 4,250lb each tire.

So... I'd inflate the front steering tires to 82 PSI. + a bit more for grandmother <grin>
And... the rear dual driving tires to 90 PSI. + ""

?Correct?

From Goodyear info I interpolated to one PSI below:
Single Dual PSI
4190 3970 80
4226 3971 81
4262 3972 82 front tires
4298 3973 83
4334 3974 84
4370 3975 85
4406 4035 86
4442 4095 87
4478 4155 88
4514 4215 89
4550 4275 90 rear tires
4575 4302 91
4600 4329 92
4625 4356 93
4650 4383 94
4675 4410 95

Regards,
Tom C.
Looks good Tom. That inflation pressure will support your GAWR which is what you should do until you can get a corner weigh done. Be aware that many suggest inflating 10% over the Goodyear table in the steer axle to minimize "river wear" which G670 tires are prone to developing on the steer axle.
__________________

__________________
Steve Ownby
Full time since 2007
2003 Monaco Signature
Steve Ownby is offline   Reply With Quote
Old 09-05-2013, 11:23 AM   #3
Senior Member
 
Fleetwood Owners Club
Spartan Chassis
Join Date: Mar 2011
Posts: 297
Quote:
Originally Posted by Tomthepilot View Post
Will I typically have higher pressures in the rear dual drivers vs front steer tires?
I know this simple tire pressure thing has been discussed at length but the more I read the more confused... well let's just say there remains an element of uncertainty for me and I may have had things bass-ackwords.

2 axle DP
Goodyear G670 RV
255/70R22.5

I realize I need actual weights but for simplified discussion:
assume a GVW of 25,500 lb
assume equal weight distribution over 6 tires:
25,500 / 6 = 4,250lb each tire.

So... I'd inflate the front steering tires to 82 PSI. + a bit more for grandmother <grin>
And... the rear dual driving tires to 90 PSI. + ""

?Correct?

From Goodyear info I interpolated to one PSI below:
Single Dual PSI
4190 3970 80
4226 3971 81
4262 3972 82 front tires
4298 3973 83
4334 3974 84
4370 3975 85
4406 4035 86
4442 4095 87
4478 4155 88
4514 4215 89
4550 4275 90 rear tires
4575 4302 91
4600 4329 92
4625 4356 93
4650 4383 94
4675 4410 95

Regards,
Tom C.
Tom,
Without a 4 corner weight, you really are guessing. I don't think the tires evenly distribute the weight the way you are figuring. If that was the case, there would be no need for a 4 corner weight. Additionally every coach that I have owned has higher pressures on the steer tires than on the duals. I would go by the recommended tire psi plate on your driver side wall until you get an accurate weight. It is safer to be over inflated for a while until you get a weigh rather than be under inflated and overloaded on the tires.
__________________
Cbones is offline   Reply With Quote
Old 09-05-2013, 11:42 AM   #4
Senior Member
 
Skip426's Avatar


 
Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 14,972
I'm , sorry but you cannot " assume equal weight distribution over the six tires"
Until you get actual weights, assume that you are loaded to your axle weight ratings.
Example . FAWR 10,000 lbs = 5,000 lbs per tire, single.
RAWR 16,000 lbs = 4,000 lbs per tire, dual.

I've always heard of more pressure in the steer tires that the duals , and that's the way mine works out from scale weights . 95 front 90 rear. with a 5 psi cushion at each.
Set your pressure high , until you get your weights , then with cold tires , lower the pressure according to the chart.
Easier to lower on the road than , find a place to pump tires up.

I see , Cbones , types faster than I do.
__________________
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Skip426 is offline   Reply With Quote
Old 09-05-2013, 11:50 AM   #5
Senior Member
 
Steve Ownby's Avatar
 
Join Date: Nov 2008
Location: Cosby, Tn
Posts: 6,399
Quote:
Originally Posted by Skip426 View Post
I'm , sorry but you cannot " assume equal weight distribution over the six tires"
Until you get actual weights, assume that you are loaded to your axle weight ratings.
Example . FAWR 10,000 lbs = 5,000 lbs per tire, single.
RAWR 16,000 lbs = 4,000 lbs per tire, dual.

I've always heard of more pressure in the steer tires that the duals , and that's the way mine works out from scale weights . 95 front 90 rear. with a 5 psi cushion at each.
Set your pressure high , until you get your weights , then with cold tires , lower the pressure according to the chart.
Easier to lower on the road than , find a place to pump tires up.

I see , Cbones , types fast than I do.
Guys,

I looked up the OPs coach and his GAWR is as follows:

Steer axle 8500
Drive axle 17000

Based on those weights then the inflation that he is using will support the coach at the maximum axle weigh rating. Agreed, he should gat a corner weight when he can but he is protected from over loading his tires at these pressures. I agree that it doesn't seem typical but the facts support him.
__________________
Steve Ownby
Full time since 2007
2003 Monaco Signature
Steve Ownby is offline   Reply With Quote
Old 09-05-2013, 12:21 PM   #6
Senior Member
 
Skip426's Avatar


 
Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 14,972
Quote:
Originally Posted by Steve Ownby View Post
Guys,
I looked up the OPs coach and his GAWR is as follows:
Steer axle 8500
Drive axle 17000
Based on those weights then the inflation that he is using will support the coach at the maximum axle weigh rating. Agreed, he should gat a corner weight when he can but he is protected from over loading his tires at these pressures. I agree that it doesn't seem typical but the facts support him.
Wow, .
__________________
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Skip426 is offline   Reply With Quote
Old 09-05-2013, 01:16 PM   #7
Member
 
Monaco Owners Club
Join Date: May 2012
Location: Louisville, KY @ the moment
Posts: 37
Wink

I do thank everyone for the quick and great responses. I do realize the need to work with actual four corner weights. For legal purposes I don't want publish numbers that might be... ah... slightly north of legal GVW. My actual tire pressures are higher than stated.

I just wanted to make sure I'm using the Goodyear data correctly.

This is our first motor home. We've had this coach for a bit over a year now. Put about 6,000 mi on it so far and I must say it's handling and predictability is far better then I ever expected and we've become very comfortable driving it.

Thanks to all,
Tom C.
__________________
Tom&Mel with a new Red Wrangler Unlimited toad & a 2005 Monaco Cayman 36PDQ to tow the toad.
Tomthepilot is offline   Reply With Quote
Old 09-05-2013, 04:00 PM   #8
Senior Member
 
JFXG's Avatar
 
Newmar Owners Club
Freightliner Owners Club
Join Date: May 2012
Location: Today? Mercer, PA
Posts: 3,620
Quote:
Originally Posted by Tomthepilot View Post
Will I typically have higher pressures in the rear dual drivers vs front steer tires?........assume equal weight distribution over 6 tires......
Quote:
Originally Posted by Skip426 View Post
I'm , sorry but you cannot " assume equal weight distribution over the six tires".....
Tom, you have what appears to be a highly atypical situation. Your numbers and premise seem accurate, but it would be wrong to assume that always to be the case. This may be why you had ongoing confusion.

As a very general rule, the GAWR breakdown runs approximately 1/3 front and 2/3 rear (as it does in your coach). In my coach its just a bit forward at 12K/19K, for a GVWR of 31K. My front tires carry 5900 lbs each (110psi), my rears about 4600 (90psi). Everyone I've talked to since I've had this coach has similar weight spread.

Now, as to your "...I don't want publish numbers that might be... ah... slightly north of legal GVW. My actual tire pressures are higher than stated...". Some may think that sounds pretty clever, but mostly its not.
__________________
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 09-05-2013, 05:02 PM   #9
Senior Member
 
Barbaraok's Avatar
 
Alpine Owners Club
Join Date: Sep 2005
Location: Traveling in North America
Posts: 1,446
Quote:
Originally Posted by Tomthepilot View Post
I do thank everyone for the quick and great responses. I do realize the need to work with actual four corner weights. For legal purposes I don't want publish numbers that might be... ah... slightly north of legal GVW. My actual tire pressures are higher than stated.
Get rid of some weight. Someone you love life might depend upon it. Why would you knowingly overweight an axle/tires?
__________________
Barbara & David O'Keeffe
Figment II (Alpine 2002 36 MDDS)
On The Road since 2006
Blog
Barbaraok is offline   Reply With Quote
Old 09-05-2013, 05:29 PM   #10
Member
 
Monaco Owners Club
Join Date: May 2012
Location: Louisville, KY @ the moment
Posts: 37
Quote:
Barbara or David wrote:
Get rid of some weight. Someone you love life might depend upon it. Why would you knowingly overweight an axle/tires?
I agree. We're seriously working on it. weight is an ongoing struggle.

Thanks,
Tom C.
__________________
Tom&Mel with a new Red Wrangler Unlimited toad & a 2005 Monaco Cayman 36PDQ to tow the toad.
Tomthepilot is offline   Reply With Quote
Old 09-06-2013, 04:48 PM   #11
Senior Member
 
Koop's Avatar
 
Join Date: Dec 2012
Location: Full Timing
Posts: 745
I've weighed my coach and my situation is similar to the OP's. Approximately one third of the weight is carried by the front axle and two thirds by the rear.
Since I have six tires, one third of the tires are on the front axle, two thirds are on the rear.

This suggests a fairly evenly balanced load per tire. The load and inflation chart indicates a dual wheel set-up needs about 10psi higher inflation than a single to carry roughly the same load.

Therefore, my rear tires are inflated 10psi higher than the front.
__________________
Mike
2003 Alpine Coach 40MDTS - 400HP Cummins ISL
Can Am Spyder Roadster
Koop is offline   Reply With Quote
Old 09-06-2013, 10:34 PM   #12
Senior Member
 
ecurb74's Avatar
 
Join Date: Feb 2013
Posts: 233
But on the rear you have 4 tires on the Axle so it seems to me that if you had 20k(arbitrary number) on rear you would divide by 4 to get the individual tire load, 5k, thus the rear would run at a lighter pressure.
__________________
Bruce & Teresa
2000 Foretravel
U320 4010
ecurb74 is offline   Reply With Quote
Old 09-07-2013, 08:37 AM   #13
Senior Member
 
Steve Ownby's Avatar
 
Join Date: Nov 2008
Location: Cosby, Tn
Posts: 6,399
Quote:
Originally Posted by ecurb74 View Post
But on the rear you have 4 tires on the Axle so it seems to me that if you had 20k(arbitrary number) on rear you would divide by 4 to get the individual tire load, 5k, thus the rear would run at a lighter pressure.
That would be true, except for the fact that tires run in a dual configuration are de-rated somewhat and so must be inflated to a higher psi to carry the same load as a tire in a single configuration. That's why the tire tables have two max weights listed at each psi level. One "S" and one "D".
__________________
Steve Ownby
Full time since 2007
2003 Monaco Signature
Steve Ownby is offline   Reply With Quote
Old 09-07-2013, 05:30 PM   #14
Member
 
Monaco Owners Club
Join Date: May 2012
Location: Louisville, KY @ the moment
Posts: 37
Quote:
Mike wrote:
I've weighed my coach and my situation is similar to the OP's. Approximately one third of the weight is carried by the front axle and two thirds by the rear.
Since I have six tires, one third of the tires are on the front axle, two thirds are on the rear.

This suggests a fairly evenly balanced load per tire. The load and inflation chart indicates a dual wheel set-up needs about 10psi higher inflation than a single to carry roughly the same load.

Therefore, my rear tires are inflated 10psi higher than the front.
Mike... and everyone else,
Thanks! Very helpful info. I feel better now about utilizing the Goodyear data to derive proper tire pressures. I'm also using a TST press/temp monitor system and it also provides a measure of comfort as we travel.


-irv2- I've learned so much about so many things here.


Regards,
Tom Charlton
__________________

__________________
Tom&Mel with a new Red Wrangler Unlimited toad & a 2005 Monaco Cayman 36PDQ to tow the toad.
Tomthepilot 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


» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 01:41 PM.


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