Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
 

Go Back   Keystone RV Forums > Keystone Tech Forums > Towing
Click Here to Login

Reply
 
Thread Tools Display Modes
 
Old 07-19-2012, 12:29 AM   #1
chris199
Senior Member
 
Join Date: Aug 2011
Location: PA
Posts: 620
Tire Pressure ....confused.....

I thought I understood..now confused by Good Sam info....
" Set inflation pressures (Note: the amount of air pressure you need depends on the weight of your fully loaded vehicle. Use the vehicle’s recommended pressure, not the pressure indicated on the tire which is usually the MAXIMUM allowable pressure)"

Have cougar 29rev...sticker says tire pressure should be 65 psi. Should I really inflate lower?

Was being diligent, using tpms, keeping it to 60 to 62.

Now what?
I believe tires are Towmax
__________________
Chris and Patty

2015 Keystone Montana 3791RD Legacy Edition, MorRyde 4000, Dual pane windows, Goodyear G rated tires.

2013 GMC Sierra 3500HD, Duramax, SLE, SRW, Crew, Hensley Trailer Saver hitch, Blue Ox BedSaver.
chris199 is offline   Reply With Quote
Old 07-19-2012, 02:54 AM   #2
therink
Senior Member
 
Join Date: May 2010
Location: Rochester, NY
Posts: 1,605
Hi, if your Towmax tires are load rated "D", then they should be inflated to 65 psi cold. Running the tires with lower psi will make them run hotter and shorten their life.
I just dumped my Towmax D's and replaced them with Maxxi E's, which are rated at 80psi. The sticker on my fiver says 65 psi, but that sticker assumes that D's are installed. I run my E's at 80psi.
__________________
Steve Rinker
Rochester, NY
2013 Outback Sydney 340FBH (12,280 lbs loaded-scale)

2015 GMC Sierra Denali 3500HD, SRW, Duramax, CC, SB (payload 3700)

https://i1109.photobucket.com/albums/...65/340FBH1.jpg
therink is offline   Reply With Quote
Old 07-19-2012, 05:35 AM   #3
Jim W
Senior Member
 
Jim W's Avatar
 
Join Date: Feb 2010
Location: Oswego Il
Posts: 820
Quote:
Originally Posted by chris199 View Post
I thought I understood..now confused by Good Sam info....
" Set inflation pressures (Note: the amount of air pressure you need depends on the weight of your fully loaded vehicle. Use the vehicle’s recommended pressure, not the pressure indicated on the tire which is usually the MAXIMUM allowable pressure)"

Have cougar 29rev...sticker says tire pressure should be 65 psi. Should I really inflate lower?

Was being diligent, using tpms, keeping it to 60 to 62.

Now what?
I believe tires are Towmax

What you should really do is weight each tire and axle load of a fully loaded trailer. Than the highest loaded tire weight for each axle will determined what the tire pressure should be.

As an example say you are using Michelins XPRIBS on you trailer, that are LT245/75R/16 LRE size tires. You need to weigh them individually to find out the proper load that that tire is supporting. Now one side of the axle tire load is 2600 lbs and the other side load is 2900 lbs than you will need to inflate the tires of that axle to 70 PSI. The 70 PSI will support 7625 LBS with this type of tire. The other axle may have a different air pressures depending on its supported load.

This is true for all RV tires all though most users of RV’s just inflated them to the maximum tire inflation that is imbedded on the side wall.
Jim W.
__________________
Jim & Jill
2010 318SAB Cougar
2008 Dodge 6.7LCummins the original 6.7L engine, w/68RFE Auto
Jim W is offline   Reply With Quote
Old 07-19-2012, 07:26 AM   #4
KanTC
Senior Member
 
Join Date: May 2010
Location: New Mexico
Posts: 1,270
Chris,

Inhale. Exhale. Relax. Just joking around...

Your trailer has 15" D rated tires (yes, probably TowMax), therefore your trailer sticker AND your tire stamp
should 'both' read 65 psi.

In a nutshell, that GS statement wouldn't apply to those of us with 15" D rated tires, but I can see why it
would be confusing. Now, that said.....

Keep tires inflated to 65, keep speed under 65, and go have fun! No more

Terri, the Chevy co-pilot
__________________
'06 Chevy 2500HD 6.6L Duramax/Allison 4x4 CC SB
2010 Laredo 265RL {SOLD}
Reese 15K Pro-series (manual slide)
KanTC is offline   Reply With Quote
Old 07-19-2012, 07:30 AM   #5
smiller
Senior Member
 
Join Date: May 2011
Location: Full-timing
Posts: 447
Quote:
Originally Posted by chris199 View Post
I thought I understood..now confused by Good Sam info....
" Set inflation pressures (Note: the amount of air pressure you need depends on the weight of your fully loaded vehicle. Use the vehicle’s recommended pressure, not the pressure indicated on the tire which is usually the MAXIMUM allowable pressure)"
That's rather poorly written because first it says to set pressure based on the vehicle manufacturer's recommendations and then it says to adjust pressure for the vehicle's actual weight... and these two values will not always be the same.

Technically the best way is to measure the weight on each tire, yadda yadda, but this usually isn't very practical, and the vehicle is not always loaded the same. In most cases it is best to inflate to maximum pressure (and thus provide maximum weight-carrying capacity) and be done with it. If you see excessive center treadwear (indicating overinflation) you can make an adjustment but usually that isn't a problem.
smiller is offline   Reply With Quote
Old 07-19-2012, 07:41 AM   #6
Festus2
Site Team
 
Join Date: Mar 2009
Location: Fraser Valley BC Canada
Posts: 7,015
More confusion?

chris199 -
There is another lengthy thread which I'm sure you've noticed --"All the tire discussion has me terrified and confused" () by X-treme which discusses tires, tire pressure and tire rims.
If you haven't been following it, there are numerous posts in that thread dealing with tire pressure which might shed some light on your question. His thread can be found in the General RV Issues section of the forum.
__________________
2008 Cougar 5th Wheel 27RKS
2005 2500 GMC Duramax
Festus2 is offline   Reply With Quote
Old 07-21-2012, 01:32 PM   #7
chuck&gail
Senior Member
 
Join Date: Mar 2011
Location: Colorado Mountains
Posts: 422
Quote:
Originally Posted by Jim W View Post
What you should really do is weight each tire and axle load of a fully loaded trailer. Than the highest loaded tire weight for each axle will determined what the tire pressure should be.

As an example say you are using Michelins XPRIBS on you trailer, that are LT245/75R/16 LRE size tires. You need to weigh them individually to find out the proper load that that tire is supporting. Now one side of the axle tire load is 2600 lbs and the other side load is 2900 lbs than you will need to inflate the tires of that axle to 70 PSI. The 70 PSI will support 7625 LBS with this type of tire. The other axle may have a different air pressures depending on its supported load.

This is true for all RV tires all though most users of RV’s just inflated them to the maximum tire inflation that is imbedded on the side wall.
Jim W.
We have weighed each wheel, set pressure to TIRE MANUFACTUERES recommendation for that load (per axle as said above) plus 5 psi for luck. Worked great so far for over 200,000 miles with only issues being a few repairable nail punctures.

Having said that, NONE of those miles were using Chinese tires. It is a choice.
__________________
Chuck
Wonderful Wife
Australian Shepherd
2010 Ford Expedition TV
2010 Outback 230RS Toybox, 5390# UVW, 6800# Loaded
Not yet camped in Hawaii, 2 Canada Provinces, & 2 Territories
I can't be lost because I don't care where this lovely road is going
chuck&gail is offline   Reply With Quote
Old 07-21-2012, 01:59 PM   #8
JRTJH
Site Team
 
JRTJH's Avatar
 
Join Date: Mar 2011
Location: Gaylord
Posts: 26,841
If you do decide to use the axle weight to establish tire pressure, make sure you're loaded the same way all the time and that when you do weigh, that the trailer weight is a "true representation" of what you really will be towing. Through the camping season the amount of "stuff" will increase as will the trailer weight. There's people on here who readily admit that they are still carrying "stuff" out to their trailer before almost every trip. Holding tanks are "sometimes full, sometimes empty, etc... All of this can dramatically change the axle weight of an RV.

So, if you reduce the pressure to a "calculated axle weight" make sure the weight stays where you "calculated"

For most of us, it's simpler and much more efficient to go with the pressure recommendation of the trailer manufacturer (for the factory installed tire size) or to go with the max pressure recommended by the tire manufacturer (for increased tire size) Monitor for tread wear with an accurate treat measurement tool and if the center of the tread wears faster, reduce pressure to accommodate, but not below the manufacturer's recommendation. I've never had that occur in 40+ years of towing.

ST tires aren't like LT tires. They have a different sidewall construction and flexing of the sidewall creates heat which is any tire's enemy. In LT tires, if you add more weight, you add more pressure to support it. Although that "can be applied" to ST tires, to really be at the "gnat's behind" on pressure, you'd need to reweigh every tire before every trip (assuming the loaded weight changes) it's just simpler to run ST tires at the recommended pressures...

Just my practice and so far, I've been able to avoid any problems with tires..... your view may vary
__________________
John



2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS
JRTJH is offline   Reply With Quote
Old 07-21-2012, 03:38 PM   #9
GMcKenzie
Senior Member
 
Join Date: Oct 2010
Location: Okanagan, BC
Posts: 916
I just inflate to the sidewall rating.

But, there is an old trick that may work well here,

Get a piece of chalk and make a line across the tread (from sidewall to sidewall). Roll the trailer forward a few feet so the tires rotate a few times. Look at the line. If the center rubs off faster, you are over inflated. If the edges rub off faster you are under inflated. The line should rub off uniformly for each tire. If one edge rubs off, you've got an alignment issue.

Make sure to do it with a normal load and completely hooked up.
__________________
2010 Cougar 30RKS
2015 GMC Sierra Max Trailer

"Drinks for 6, Dinner for 4, Sleeps 2"
GMcKenzie is offline   Reply With Quote
Old 07-21-2012, 06:25 PM   #10
CWtheMan
Senior Member
 
CWtheMan's Avatar
 
Join Date: Feb 2010
Location: Taylors, SC
Posts: 3,031
Here is a NHTSA reference that tells the reader straight out who is responsible for setting correct tire pressures. Remember, correct and recommended tire pressures are synonymous.

I post this reference because it makes it very clear that tire manufacturers DO NOT set tire pressures.

http://www.safercar.gov/Vehicle+Shop...nd+Load+Limits

Almost all load inflation tables found on the internet are without instructions. That’s because they were written for the tire industry at large. On the same line, using scaled weight in conjunction with load inflation tables is also almost always without instructions. The key instruction missing is when using load inflation tables to adjust tire pressures is to NEVER use less than the recommended tire pressures found on the vehicle labeling or it’s owner’s manual.

Vehicle tire pressures all revolve around the same regulations and the procedures remain consistent across all designs.

CW
CWtheMan is offline   Reply With Quote
Old 07-21-2012, 08:40 PM   #11
fla-gypsy
Senior Member
 
Join Date: May 2012
Location: North Florida
Posts: 1,241
Don't overthink it. Follow the manufacturers recommendation sticker
__________________
2006 Keystone Hornet 29RLS (The Cracker Cabana)
2009 F-250 SuperDuty CC 6.8L/4.10 (The Black Pearl)
fla-gypsy is offline   Reply With Quote
Reply

Thread Tools
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
Forum Jump

» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3
Disclaimer:

This website is not affiliated with or endorsed by the Keystone RV Company or any of its affiliates in any way. Keystone RV® is a registered trademark of the Keystone RV Company.


All times are GMT -8. The time now is 12:54 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.