Go Back   iRV2 Forums > TRAVEL TRAILER, 5th WHEEL & TRUCK CAMPER FORUMS > 5th Wheel Discussion
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 03-24-2012, 03:27 PM   #29
Senior Member
 
Dunner's Avatar
 
Join Date: Jun 2011
Location: Phx, Arid~zona
Posts: 11,106
Quote:
Originally Posted by wa8yxm View Post
I think that if you take 10 tire pressure gauges and make a tank with a pressure regulator so you can keep the pressure in the tank within 1/2 PSI of a "reference" and then take readings with all 10 gauges you might well find one that reads 5-10 PSI higher than the rest... Or lower.

And I think the tire makers know this.

So, less your gauge is lab calibrated... You don't really know what pressure is in the tire.
Someone posted in another thread about getting a "calibrated" air pressure gauge from NAPA. Anybody remember that and/or have a part # or description? I have about 10 gauges, some high quality and some not so high quality and would like to find at least one that is accurate. I have one of these, but it only goes to 60 PSI.
Accutire Racing Air Gauge
__________________

__________________
2004 32' National Sea Breeze 1311 Class A on a F-53 Chassis, CHF, TST TPMS, 5Star Tune.
If Dunner (RVM23) can't fix it, it ain't broke!
Cheap Handling Fix Poll. Click Here to vote?
Dunner 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 03-25-2012, 12:19 AM   #30
Senior Member
 
Winnebago Owners Club
Workhorse Chassis Owner
Join Date: May 2011
Location: Central, South Carolina
Posts: 290
Get a Bourdon Tube gauge with a HELICOIL movement, it will tolerate all kinds of abuse.
__________________

__________________
garyspang is offline   Reply With Quote
Old 05-01-2012, 08:34 AM   #31
Junior Member
 
Join Date: Aug 2011
Posts: 12
Quote:
Originally Posted by ottffss View Post
And therein lies the critical distinction. For whatever reason, "trailer" (ST) tires seem to follow slightly different manufacturer guidelines than "vehicle" (moho, truck, car, etc.) tires.

My post deals with vehicle tires, NOT trailer tires. I failed to completely describe that.
As with all things, it depends.

Page 2-04 in the 2008 TRA yearbook has the same cold inflation and loading modifiers for tires listed in LTM-4A. That table contains the LT tires. It does mention that tires with a service description are not covered by the inflation and loading modifiers.

So it depends on what KIND of vehicle tires. P, LT, truck-bus, other...?
__________________
N3YMY is offline   Reply With Quote
Old 05-01-2012, 10:44 AM   #32
Senior Member
 
wandering1's Avatar
 
Join Date: Nov 2007
Location: NC
Posts: 450
Send a message via ICQ to wandering1
Rep didnt know what he was talking about. Over or under inflated tires will cause heat build up which damages tires. What did the idiot think the PSI is on the sidewalls for? Check with the tire manufacturer if you want the facts not the dealer.
__________________
Wandering1
wandering1 is offline   Reply With Quote
Old 05-02-2012, 12:12 AM   #33
Senior Member
 
VanDiemen23's Avatar
 
Join Date: Oct 2010
Posts: 778
as stated before, underinflated tires overheat due to sidewall flex, overinflated tires do not because there's less flex.
__________________
VanDiemen23 is offline   Reply With Quote
Old 05-02-2012, 12:22 AM   #34
Senior Member
 
Mr_D's Avatar
 
Solo Rvers Club
iRV2 No Limits Club
Join Date: May 2011
Location: Vancouver, WA
Posts: 28,386
Quote:
Originally Posted by Dunner View Post
Someone posted in another thread about getting a "calibrated" air pressure gauge from NAPA. Anybody remember that and/or have a part # or description? I have about 10 gauges, some high quality and some not so high quality and would like to find at least one that is accurate. I have one of these, but it only goes to 60 PSI.
Accutire Racing Air Gauge
That was probably me. Yes I just went to NAPA and found that they had a certified gauge. Looked like a regular stick truck gauge other than it was finished in black crackle paint. Looked at the NAPA site and can't find it.
__________________
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft
Charter Good Sam Lifetime Member, FMCA, SKP
RV'ing since 1957, NRA Benefactor Life, towing '14 CR-V
Mr_D is offline   Reply With Quote
Old 05-02-2012, 02:03 AM   #35
Registered User
 
Vintage RV Owners Club
Gulf Streamers Club
Join Date: Oct 2010
Location: Indiana
Posts: 4,954
Quote:
Originally Posted by VanDiemen23 View Post
I've been watching this thread for a while and frankly, most of the info in it regarding overinflation and tire safety, is malarky.

I've raced cars and been around people at the highest levels of motorsport since the 1980s, talked frequently with tire engineers, and after reading this last night, wrote a friend who's a tire engineer and discussed this thread, as well as compared notes on our experiences with trailer tires over the years.

First of all, tire durability is overwhelmingly related to running temperature. Running temperature goes up because of flexing in the tire carcass. The higher the pressure the less flexing and lower overall tire temperatures (especially in radials).

Tires have about a 3x safety factor in inflation - you can put more than 90 psi in a 32 psi rated tire when new and it won't catastrophically fail. Therefore a reasonable amount of cold overinflation combined with an expected amount of hot pressure increase is not going to cause failure. This is especially true when running at high speed in hot (desert sunny) conditions. I have an old college roommate who used to work the oil fields in Saudi. They used to run standard passenger car tires (32 to 36 psi) at 45-50 or else a blowout was a serious risk (they frequently ran over 100 mph out in the boonies).

I don't know what police departments do, but when I autocrossed cars we used to put 45 psi or more in higher profile tires (this was before 50 series were widespread) to keep the tire on the rim at high cornering loads - you have to stiffen the sidewall on a radial with more pressure when running at extremes or bad things will happen. Bias tires are not as much of a problem.

That's not to say there aren't tradeoffs. Inflation pressures for a given tire manufacturer and size are designed to produce a footprint that maximizes traction and durability under normal use. Raise the load and you need more pressure to maintain that footprint and lower running temperature. If you overinflate the tire it "beachballs" and reduces the load on the outer ribs, increasing the wear on the center of the tire. Because the footprint reduces in both length and width, traction capacity goes down.

If you really want to know how happy your tires are you have to get a contact pyrometer and push the needle into the tread blocks and look at temperature across the surface of the tire IMMEDIATELY after a half hour or so of intended use. For something like trailer tires and rear tires of a MH or tow vehicle, the temps should be within 10 degrees or so across the tread and consistent across all four tires - or else you have a loading issue or alignment issue. On front axles, they should be 20 deg or so hotter on the inside edge than the outside - this is due to camber. IR non-contact pyrometers are useless in this application. I'd guess they ought to be under 175 deg, but I haven't found a reference. Race tires run over 200 deg. I've commonly seen 235!

What is not BS is the warning on rated speed. I frequently pull my trailers at 75-80 with the truck, but no more than 65 with the MH. OUT here in the Mojave, it's HOT. On my old toyhauler I went through a set of Goodyear Marathons and a set of Denman STs with 7 belt failures. On my current trailer, I had almost two years of use with no noticeable tire wear using the standard cheap chinese junk OEM tires - all towed behind my MH. Then I took a a fast trip to Tucson to pick up another race car, towed it with the truck. Got home and the front two tires on the trailer are now neither round nor flat across the tread, with heavy wear on the inside. NONE of these tires were run underinflated or overloaded - in fact, they were about 20% under max load.

When I compared notes with my tire engineer friend, he indicated after 20 years of no problems with Firestone 440s, he switched to carlisles and had a blowout. Failure analysis showed no signs of rubber adhesion in the cords - a sign of poor manufacturing quality. He's now using made in USA LT tires on his trailer, rated at 44 psi but inflated to 50 to add lateral stiffness and make them run cooler - because while the LTs don't offer the sidewall protection of an ST, they are safer at highway speeds. I'm now considering going that route or the one below.

A previous post included links to the GY RV guide - but that's not the only GY reference out there - see:

http://www.tirerack.com/images/tires...plications.pdf

An interesting tidbit in there:
"Special Trailer (“ST”) Tires
Goodyear Marathon trailer tires are widely used in a variety of towable trailer applications and are designed and branded as “ST” (Special Trailer) tires.
•
Industry standards dictate that tires with the ST designation are speed rated at 65 MPH (104 km/h) under normal inflation and load conditions.
•
Based on these industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph (106 km/h and 121 km/h), it is necessary to increase the cold inflation pressure by 10 psi (69 kPa) above the recommended pressure for the rated maximum load.
o
Increasing the inflation pressure by 10 psi (69 kPa) does not provide any additional load carrying capacity.
o
Do not exceed the maximum pressure for the wheel.
o
If the maximum pressure for the wheel prohibits the increase of air pressure, then the maximum speed must be restricted to 65 mph (104 km/h).
o
The cold inflation pressure must not exceed 10 psi (69 kPa) beyond the inflation specified for the maximum load of the tire."
To the original poster, your mileage may vary, but it appears a ~10-20% overinflation will increase speed margin but not load margin, and have no other adverse effects on safety.
Have to agree with everything said here..

I once saw a tire guy take a tire to over 80 psi. It blew off the machine, hit the rafters, and rolled/bounced down the street.. tire was still intact.

Old tire guys use to say 'if its a slow leak at 35, it'll be a big one at 60' and then fill it to that..

On the road, an overinflated tire will simply have a reduced footprint... to a point. After which you need to be concerned with damage from sticking obstacles such as potholes and curbs. But, if your that high up in psi, you will prolly be looking pretty silly with you your ballon tires on an RV
__________________
Midniteoyl is offline   Reply With Quote
Old 05-02-2012, 03:23 AM   #36
Senior Member
 
Dunner's Avatar
 
Join Date: Jun 2011
Location: Phx, Arid~zona
Posts: 11,106
Quote:
Originally Posted by Mr_D View Post
That was probably me. Yes I just went to NAPA and found that they had a certified gauge. Looked like a regular stick truck gauge other than it was finished in black crackle paint. Looked at the NAPA site and can't find it.
Don't think I want a stick gauge. Dial or digital.
__________________
2004 32' National Sea Breeze 1311 Class A on a F-53 Chassis, CHF, TST TPMS, 5Star Tune.
If Dunner (RVM23) can't fix it, it ain't broke!
Cheap Handling Fix Poll. Click Here to vote?
Dunner is offline   Reply With Quote
Old 05-02-2012, 03:22 PM   #37
Senior Member
 
FastEagle's Avatar
 
Join Date: Sep 2009
Posts: 819
"The Vehicle Manufacturer Determines The Correct Tire Pressure (s) For The Tires On Your Vehicle." (NHTSA)

FastEagle
FastEagle is offline   Reply With Quote
Old 05-02-2012, 03:35 PM   #38
Senior Member
 
Ramblin's Avatar
 
National RV Owners Club
Workhorse Chassis Owner
Ford Super Duty Owner
Carolina Campers
Join Date: Aug 2011
Posts: 2,253
Quote:
Originally Posted by FastEagle View Post
"The Vehicle Manufacturer Determines The Correct Tire Pressure (s) For The Tires On Your Vehicle." (NHTSA)

FastEagle
What if the vehicle manufcturer recommends a higher pressure than the max pressure on the sidewall? Could happen, no?
__________________
2002 National Dolphin LX 6356
Workhorse W-22 chassis
Don't believe everything you think.
Ramblin is offline   Reply With Quote
Old 05-02-2012, 04:05 PM   #39
Moderator Emeritus
 
RustyJC's Avatar


 
Texas Boomers Club
Join Date: Jul 2000
Location: Cypress, Texas USA
Posts: 8,854
Quote:
Originally Posted by Jnspenc View Post
Ok, about the tire pressure. My sidewalls say my PSI should be 110. In my RV, (Heartland Landmark) in the cabinet it states tire pressure 110. Now the side panel next to VIN plate states 80 psi. Ok guys and gals, whick one do I go by???
It sounds like you have load range G tires (Goodyear G614 RST, perhaps?) installed on your 5th wheel - the LT235/85R-16 RST tires are rated for max load of 3750 lbs @ 110 PSIG. The side panel sticker is based on load range E tires such as the Goodyear Wrangler HT which, in an LT235/85R-16 size, are rated for max load of 3042 lbs @ 80 PSIG (an ST tire may have a higher rating).

If this was a factory wheel & tire upgrade (an option, perhaps), that's fine. A potential pitfall that I'd watch out for, however, is what inflation pressure the wheels are rated for. Load range G wheels are substantially thicker in cross-section than load range E wheels, and the Goodyear G614 RST webpage specifically states that special wheels are required to utilize those tires.

If the factory upgraded both the tires and wheels, you're in good shape to go up to the 110 PSIG max. If, on the other hand, you have load range E wheels, you're limited to their maximum inflation pressure that should be stamped on the rim (probably on the inside of the wheel) - typically, 80 PSIG max.

Rusty
__________________
2016 Ram Longhorn 3500 Dually 4x4 CCLB, 385/900 Cummins, Aisin AS69RC, 4.10
2014.5 DRV Mobile Suites 38RSSA #6972
Come join us on a TEXAS BOOMERS rally!
RustyJC is offline   Reply With Quote
Old 05-02-2012, 09:14 PM   #40
Senior Member
 
Join Date: Apr 2004
Posts: 1,077
Hi performance vehicles and other lightweight cars can get by with increased pressures above max. Just like the old cross country race by the car manufatures in the '50s/'60s to see who got this years bragging rights for the best mpgs. They would pump those old 32 psi rated tires on up to 45-50 lbs.
However a load carrying tires or wheel on a truck is a different matter.

I've pulled equipment trailers up to 22k lbs with LDT's (mostly DRW one tons) since the '60s commercially and non commercially.
I've seen and I've personelly split steel wheels and blown out tires (zipper ruptures) from inadvertently using more pressure then the tire/wheel was rated for.

My advise is never overinflate a tire on a truck. The tire manufacurer knows that a E tire cold set to 80 psi will increse pressure at high ambiet temps and high speeds. Adding too much pressure above max isn't a wise choice.
__________________
'03 Dodge 2500 Cummins HO 3.73 NV5600 Jacobs
'98 3500 DRW 454 4x4 4.10 crew cab
'97 Park Avanue RK 28' 2 slides
JIMNLIN is offline   Reply With Quote
Old 05-02-2012, 09:22 PM   #41
Senior Member
 
VanDiemen23's Avatar
 
Join Date: Oct 2010
Posts: 778
However, force is force. The tire cares not if force is applied by pressure, load or RPM. However, pressure is not increased by speed, but the forces in the cords increase by speed squared. If I had to guess I'd bet your tire failures were caused by a non-catastrophic split-rim failure, followed by air loss, followed by a low-pressure overheat failure of the tire.
__________________
VanDiemen23 is offline   Reply With Quote
Old 05-03-2012, 07:36 PM   #42
Senior Member
 
Join Date: Apr 2004
Posts: 1,077
Quote:
Originally Posted by VanDiemen23 View Post
However, force is force. The tire cares not if force is applied by pressure, load or RPM. However, pressure is not increased by speed, but the forces in the cords increase by speed squared. If I had to guess I'd bet your tire failures were caused by a non-catastrophic split-rim failure, followed by air loss, followed by a low-pressure overheat failure of the tire.
Nothing wrong with the wheels. Nothing but too much pressure in the tire.
__________________

__________________
'03 Dodge 2500 Cummins HO 3.73 NV5600 Jacobs
'98 3500 DRW 454 4x4 4.10 crew cab
'97 Park Avanue RK 28' 2 slides
JIMNLIN is offline   Reply With Quote
Reply

Tags
heartland



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
Auto Park Brake converted to Manual Lever the_dieter Workhorse and Chevrolet Chassis Motorhome Forum 181 09-10-2015 08:13 AM
New to us 2000 Mountain High Summit SteveLevin New Rig Show-Off! 20 04-11-2015 08:29 AM
Favorite Dishes to prepare while RV'ing Wolfpack Fan iRV2.com General Discussion 42 03-30-2012 02:28 AM
Not New, but New to Us. vapor3000 New Rig Show-Off! 18 03-29-2012 07:38 PM
Thoughts on Tires Gthree iRV2.com General Discussion 28 03-25-2012 02:43 PM

» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 03:32 PM.


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