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


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 07-06-2013, 07:44 AM   #501
Rivet Master
 
MaxAB's Avatar
 
1977 31' Sovereign
1985 25' Sovereign
South Central Rockies... , "...'Stream'n the Dream" thru the USA
Join Date: Apr 2009
Posts: 535
Images: 39
Kiss...

CapriRacer said it well above: "If you want a "Set it and Forget it" approach to things: Set the pressure on a cool day - in the 40's. Or adjust the starting pressure so it is OK at 40°F. A bit of over pressure is not significant - including tire wear."

In a galaxy far away and in my previous life as a navy carrier pilot, we flew with the main mounts inflated with pure nitrogen at 300psi to withstand extreme energetic cat shots and the pounding forces of arrested landings. Pressures were monitored before and after every flight - in some cases, that meant 6-8 times daily.

Point being, if you really want a "Set and Forget it" solution, as Capri suggests - pay the extra few bucks for Nitrogen, or get it free at some tire shops.

There's some benefits in running Nitrogen in both your TV and AS:

1. Nitrogen is a gas and is still affected by changes in ambient temperature (about one psi for every 10° Fahrenheit). Nitrogen filled tires will require pressure be added during the fall/winter months as ambient temperatures and tire pressures drop. Nitrogen is good but can't change the laws of physics.

2. Nitrogen reduces the loss of tire pressure due to permeation through rubber over time by about 30%. This helps maintain the required tire pressures a little longer, but doesn’t eliminate the need for monthly tire pressure checks. This is good for people who choose the "Set it and Forget it" approach.

3. Nitrogen is non-corrosive and will reduce oxidation and rust due to the absence of oxygen and moisture. This will help minimize wheel corrosion to promote better bead sealing. Tires that are used routinely will be replaced long before any life benefit would be received by using Nitrogen. This is most beneficial for those who use their Airstreams infrequently.

4. Nitrogen is a dry gas and will not support moisture that could contribute to corrosion of the tire’s steel components (bead, sidewall reinforcement and belts) due to the absence of moisture over extended periods of time. However it’s important to remember that atmospheric pressure is constantly pushing oxygen and moisture into the rubber from the outside of the tire. This is especially good for low mileage those who don't wear out their tires quickly or those that run average annual mileages but use long wearing radial (60K and 80K warranted) tires.

5. Nitrogen assures more consistent pressure increases due to increases in operating temperatures in environments such as the Rocky Mountains/Sierra Nevada (low morning, high afternoon temps) because of the absence of moisture.

6. It is OK to use standard air if pressure adjustments are required when a local source of Nitrogen can’t be found during a trip. While this reduces the benefit of higher Nitrogen content, it is far better than running the tires under-inflated in search of a source for Nitrogen- thus, increasing the chance of a tire failure. Often the original Nitrogen provider will refill the tires for free or a nominal cost when the driver returns to his hometown.

My final $0.02, KISS: find a comfortable personal balance between using your TPMS, IR temp gauge, manual pressure gauge, multiple daily monitoring efforts, and keeping your entire running gear system safe and effective while all the time maintaining the peace of mind that you won't have a catastrophic tire failure as you're 'streaming down the interstate.
MaxAB is offline   Reply With Quote
Old 07-08-2013, 11:47 AM   #502
3 Rivet Member
 
2014 30' International
DFW Airport , Texas
Join Date: Jul 2013
Posts: 144
I was referring to the NI STP definition that we also use to define engine performance in a aerospace and automotive analyses. But given the logical use of percentages to figure psi change with temp the guideline at the higher inflation levels of E,F and beyond works out more closely to 2 psi per 10 deg F. Meaning that at a running temp of say 130 F (Summer in the South on the Sunny side) that is a delta of 60 deg or Plus 12 psi putting the tire at 92 psi assuming you started at STP and nominal max inflation of 80 psi. By my math (often faulty) thats an increase of 15% at which point my Pressure Pro TPMS would be hollering loudly. Put another way, if the internal tire temp hits 130 by most definitions you have a problem. I have seen something close to this at 127 deg at 100 ambient and 130 surface (by IR thermometer) so was sailing close to a limit that had I been in say AZ rather than OK and TX would have caused me to pull over.

As for Nitrogen as the panacea of all these problems my experience also matches all the points made with one proviso - its still hard to find outlets equipped to deflate the tire (without losing the bead seal) and reflating. Had I that opportunity I would grab it. The major issue IMO is not the stability of N2 but rather the lack of moisture in the content. That moisture creates effectively a super heated steam inside the tire that makes any amount of temperature problem that much worse. Like a sauna effect!

Final point - the ability to fill and forget is a luxury that is only obtainable by having a rig that can be operated at a considerable (25%) margin below the max load for the tire. I unfortunately do not have such equipment and its not made by anyone anywhere so I am trying to learn all I can about the risks of operating so close to the limits of E, F and G tires as opposed to China Bombs.
Vlamgat is offline   Reply With Quote
Old 07-08-2013, 11:55 AM   #503
3 Rivet Member
 
2014 30' International
DFW Airport , Texas
Join Date: Jul 2013
Posts: 144
Quote:
I have a 3/4 ton diesel truck and a trailer with a GVW rating of 10,000 pounds. I have a HawksHead TPMS.

However what are your axle loads realtive to the GVW and the GCVW? when I did as you have I was bitten by the fact that although I was below my GVW and GCVW I was over the axle load limit as imposed by the rear tires because of the effect of a 1400 lb hitch weight.

A gotcha thats only solved with 17.5 or 19.5 wheels G rated tires
Vlamgat is offline   Reply With Quote
Old 07-08-2013, 01:05 PM   #504
Rivet Master
 
2005 19' Safari
GLENDALE , AZ
Join Date: Aug 2004
Posts: 2,453
Vlamgat, I'm unsure where you got a delta of 60 degrees. While I have not worried about calculating the temperature and pressure increase throughout the day. I have seen no pressures like your calculations predict.

Here in Phoenix, when I check the tires before pulling out, the ambient air temperature at 8:00-9:00 AM is already around 95 degrees headed to 100+ in another hour or two. The overnight lows are around 90, and that's at 2:00 AM.

With daytime highs around 110-115 most days, that's only a difference of around 15 degrees (95 to 110), maybe 20.

If the temperature a couple of feet above blacktop is 120 degrees, that's still only 25 degrees, which equates (on your 2 psi/10 degree differential) to a 5 psi increase.

I maintain 80 psi in our Michelin XPS Ribs, all year; and in the summer, after verifying 80 psi at 8:00 AM, I used to measure tire pressure increases of zero to 2 psi after driving an hour.

Note: I no longer check tire pressure while on the road; and instead, use an IR thermometer to monitor changes in tire temperature. If the temperature is the same as the last stop and a tire doesn't look low, I assume the tire pressure is still OK. I acknowledge that this isn't very scientific, but it's better than not checking at all.

From years of towing in the desert southwest, I have never seen an increase in tire pressure from 80 to 92 psi while driving. And, while I would never intentionally increase the cold tire pressure to 92 psi, a tire probably wouldn't be damaged by this unless run at this pressure consistently, which would cause abnormal tire wear. Tire manufacturers state that a slight increase in psi is normal; and pressure should not be reduce when hot, if cold reading was at or below the maximum sidewall pressure.

I understand your concern regarding tires and tire pressure. However, from a practical standpoint, about all one can actually do is install the best tires one can afford (or justify), pump them up to the maximum sidewall pressure, and hope for the best. That's what we did by replacing our ST tires with XPS Ribs and inflating them to 80 psi. And, after verifying 80 psi before pulling out, we don't worry about our tires again.
Phoenix is offline   Reply With Quote
Old 07-08-2013, 04:06 PM   #505
Chief Chili Cook
 
newroswell's Avatar
 
2010 30' Flying Cloud
Bakersfield , California
Join Date: Feb 2009
Posts: 738
Quote:
Originally Posted by Vlamgat View Post
was below my GVW and GCVW I was over the axle load limit as imposed by the rear tires because of the effect of a 1400 lb hitch weight.

A gotcha thats only solved with 17.5 or 19.5 wheels G rated tires
How did you measure the 1400 lb hitch weight? Our 30' Flying cloud is right at 800 lb based on CAT scales and double checked with a friends Sherline scale at a rally sitting in a campground with full propane, upgraded batteries and full water tank. Airstream specifications have you at 880, with propane, without options.
__________________
The NSA -- The only part of the government that listens.
newroswell is offline   Reply With Quote
Old 07-09-2013, 06:33 AM   #506
3 Rivet Member
 
2014 30' International
DFW Airport , Texas
Join Date: Jul 2013
Posts: 144
The delta is between STP at 68 deg and your starting temp at say 100 - already 30 degrees or very nearly a 6 psi plus needed for your tire. Meaning when you pull out and assuming E LR, you should be at 85 psi minimum. On my Gs I would be at 115 psi.

And while I agree that all we can do is buy the best and hope for the rest, my concern is there is no real way to know what is best. The manufacturers tell us nothing about how they qualify their tires for the load ratings and whether the rating is for sustained use in US highway conditions in all weathers or whether they are ideal settings on a constantly loaded roller in a factory.

And contrary to what has been written here, the Michelin and GY factories I visited did not test in 100 deg ambients. It was room temp (working Lab) on a smooth roller with no flex on the sidewalls turning at 75 mph. Thats where the so called safety margin comes from being 10 mph plus to the advised maximum speed. However add the real world of constant flex, higher ambient, lower unadjusted initial inflation, road debris, occasional over loading because of front to rear or left to right axle loads and surface temps that reach above 150 - now how long should the tire last. no one knows. Its a gamble that we play with in our tow vehicles using trial and error. That is until their is sufficient systemic proven failures with sufficient damage or injury to warrant the attention of the plaintiff's bar, we take it on the wallet.
Vlamgat is offline   Reply With Quote
Old 07-09-2013, 06:36 AM   #507
3 Rivet Member
 
2014 30' International
DFW Airport , Texas
Join Date: Jul 2013
Posts: 144
Quote:
Originally Posted by newroswell View Post
How did you measure the 1400 lb hitch weight? Our 30' Flying cloud is right at 800 lb based on CAT scales and double checked with a friends Sherline scale at a rally sitting in a campground with full propane, upgraded batteries and full water tank. Airstream specifications have you at 880, with propane, without options.
I bought a scale and weighed it. I also have a scooter garage built into the front of my AS where I store a couple of Hondas. Also makes for a steadier tow than putting them at the rear where it would have messed up the bathroom plumbing of my International.
Vlamgat is offline   Reply With Quote
Old 07-09-2013, 09:21 AM   #508
Chief Chili Cook
 
newroswell's Avatar
 
2010 30' Flying Cloud
Bakersfield , California
Join Date: Feb 2009
Posts: 738
Quote:
Originally Posted by Vlamgat View Post
I bought a scale and weighed it. I also have a scooter garage built into the front of my AS where I store a couple of Hondas. Also makes for a steadier tow than putting them at the rear where it would have messed up the bathroom plumbing of my International.
Now it all adds up! Thanks, and I'm sure I'm not the only one that would love to see photos of the garage mod.
__________________
The NSA -- The only part of the government that listens.
newroswell is offline   Reply With Quote
Old 07-10-2013, 06:05 AM   #509
CapriRacer
 
CapriRacer's Avatar
 
I'm in the , US
Join Date: Sep 2012
Posts: 989
Quote:
Originally Posted by Vlamgat View Post
.........And contrary to what has been written here, the Michelin and GY factories I visited did not test in 100 deg ambients. It was room temp (working Lab) on a smooth roller with no flex on the sidewalls turning at 75 mph.......
Be aware that many places have their own test procedures that differ from the DOT test procedure. NHTSA takes that into account when (and if) they review the test data. If the testing is different, then a correlation has to be demonstrated.

So it shouldn't be a surprise that some folks test at room temperature. They may claim they are doing DOT compliance testing - and in a manner of speaking they are.
CapriRacer is offline   Reply With Quote
Old 07-10-2013, 06:16 AM   #510
3 Rivet Member
 
2014 30' International
DFW Airport , Texas
Join Date: Jul 2013
Posts: 144
Rue - like most government regs, DOT compliance is hardly more than a seal of approval. Even the China Bombs claim DOT approval on the sidewalls. Who knows what that means: the tire is mostly round !
Vlamgat is offline   Reply With Quote
Old 07-10-2013, 11:57 AM   #511
Master of Universe
 
Gene's Avatar
 
2008 25' Safari FB SE
Grand Junction , Colorado
Join Date: Sep 2007
Posts: 12,694
Yes, it is easy to overthink this. My question about going from 40˚ to 90's in one day of driving was to show there are situations where a simple rule doesn't apply and there's no reason to worry.

One time that happened, I started in northeast Montana and then drove west and south and my TPMS started screaming at me (feels like screaming after a while) and the red light kept flashing. So I stopped and let some air out; solved. If I had started out the day at 55˚, probably I would have had no alerts and no problem. So letting out 3 or 4 psi is equivalent (roughly) to starting out at higher ambient temps.

I too have an infrared temperature gauge. While it is fun to measure the temperature of my arm, my knee, the A/C vents, my wife's earlobe, and thus is worth buying, I never bother to measure tire or wheel bearing temp unless something else indicates a problem worth looking into. The TPMS system gives me enough info (including tire temp) almost all the time.

Gene
__________________
Gene

The Airstream is sold; a 2016 Nash 24M replaced it.
Gene is offline   Reply With Quote
Old 07-11-2013, 10:23 AM   #512
Rivet Master
 
switz's Avatar

 
2014 31' Classic
2015 23' International
2013 25' FB International
Apache Junction , Arizona
Join Date: Sep 2012
Posts: 6,214
Images: 9
I installed Centramatics and the 15" Michelins on the 25FB International after getting it home. That trailer has a GVW of 7,300 pounds and a tongue weight loaded of 1,175 pounds. That means the trailer axles are supporting about 6,125 pounds. The 10% derated capacity of the four 15" Michelin LTX (P) 235/75R15 XL tires at 50psi is 7,932 pounds which is a substantial safety margin exceeding 25%.

We have now ordered a 2014 27FB Classic which has a GVW of 9,000 pounds and perhaps will have a 1,100 pound tongue weight. For conversation purposes, the axles would be supporting about 7,900 pounds. Thus the 15" Michelins would have no safety margin if the trailer were fully loaded.

That means that I will order five Michelin LT 225/75R16RE M/S2 tires with SenDel T03-66655T wheels just like Airstream will install on the Eddie Bauer models or install on a trailer at the factory. The four 16" Michelin tires have a load capacity of 10,720 pounds at 80psi. That means we have a load safety factor exceeding 35%.

I selected the M/S2 over the XPS Rib for the wet braking characteristics and the Green X rating on the tire.
__________________
WBCCI Life Member 5123, AIR 70341, 4CU, WD9EMC

TV - 2012 Dodge 2500 4x4 Cummins HO, automatic, Centramatics, Kelderman level ride airbag suspension, bed shell

2014 31' Classic w/ twin beds, 50 amp service, 1000 watt solar system, Centramatics, Tuson TPMS, 12" disc brakes, 16" tires & wheels
switz is offline   Reply With Quote
Old 07-11-2013, 01:01 PM   #513
Master of Universe
 
Gene's Avatar
 
2008 25' Safari FB SE
Grand Junction , Colorado
Join Date: Sep 2007
Posts: 12,694
Good choice switz. We've had the Michelins M+S (2 wasn't yet available) for 30,000 miles and they ride and wear great. They don't lose air like Marathons. The biggest problem is wearing them out before it is time to change them.

While a lot of people say tires are ready to be changed after 5 years, Michelin says a much longer period is quite possible: http://www.michelinman.com/mediabin/...l_Bulletin.pdf

Gene
__________________
Gene

The Airstream is sold; a 2016 Nash 24M replaced it.
Gene is offline   Reply With Quote
Old 07-11-2013, 01:19 PM   #514
cwf
Rivet Master
 
cwf's Avatar
 
1999 34' Excella
Currently Looking...
Hillsboro , Texas
Join Date: Feb 2013
Posts: 6,406
Images: 2
Blog Entries: 2
My dog lives to chase the red dot! When the beep happens he really perks up!
__________________
Peace and Blessings..
Channing
WBCCI# 30676
cwf is offline   Reply With Quote
Old 07-11-2013, 05:06 PM   #515
Contributing Member
 
Pahaska's Avatar
 
2018 Interstate Grand Tour Ext
Austin (Hays County) , Texas
Join Date: Jun 2002
Posts: 7,164
Images: 4
Quote:
Originally Posted by Gene View Post
While a lot of people say tires are ready to be changed after 5 years, Michelin says a much longer period is quite possible: http://www.michelinman.com/mediabin/...l_Bulletin.pdf
Gene
When I had my tires mounted, the tire shop gave me a card that Michelin provides that has a series of black to gray squares. The square that matches the tire gives an estimate of the time left before the tire should be replaced.

As my trailer is in covered storage, I find very little color change in the sidewalls over time. The Carlisle E tires I took off look like new tires, but good riddance. Carlisle E tires destroyed the sides of three of my Airstream acquaintances. The tread separated without the tires losing air. The loose tread wiped out the wheel well and the plumbing. My old tires/wheels will soon appear on a friend's utility trailer.
__________________
John W. Irwin
2018 Interstate GT, "Sabre-Dog V"
WBCCI #9632
Pahaska is offline   Reply With Quote
Old 07-11-2013, 05:24 PM   #516
Contributing Member
 
Pahaska's Avatar
 
2018 Interstate Grand Tour Ext
Austin (Hays County) , Texas
Join Date: Jun 2002
Posts: 7,164
Images: 4
Lug bolt problem

When I replaced the rear curbside wheel, I found it difficult to get one of the lug nuts off and a second nut was a bit cranky. This was strange, because the last time that wheel was off was when a very competent Airstream mechanic packed my bearings about a year ago while I watched. I carry my own torque stick and torque wrench, so the nuts have never been overtightened.

When I replaced the lug nuts, one would not go on at all, while the other went on hard. I checked the worst bolt end with a magnifier and found what looked for all the world like a splatter of weld in the threads. I tried with a Dremel tool and thread chaser to clean up the bolt, but with no success. I think the glob was material from the threads that had been dragged to that point and bonded to the bolt.

Off came the wheel and disc brake hub. I pounded out one lug bolt and took it to A-Line to buy 6 like it. I didn't have a part number, but they gave me a good match that was, perhaps, 1/32" longer. I also put on new lug nuts. Everything is back together again tonight after most of an hour working in the shade at 102 degrees.

Folks with Kodiak disc brakes might like to write down the lug bolt part number for reference. It is "DOR 610-394 wheel bolt 1/2-20x1-29"
__________________
John W. Irwin
2018 Interstate GT, "Sabre-Dog V"
WBCCI #9632
Pahaska is offline   Reply With Quote
Old 07-11-2013, 09:32 PM   #517
Contributing Member
 
Pahaska's Avatar
 
2018 Interstate Grand Tour Ext
Austin (Hays County) , Texas
Join Date: Jun 2002
Posts: 7,164
Images: 4
By the way, in reference to my last post above. I have always torqued my wheel lugs on this trailer to 85 foot pounds as specified by ALCOA for my old wheels. I have an 85 foot pound torque stick. I also have a 100 foot pound maximum torque wrench which has been set to 85 fp each time I mount a wheel. I check torque before every trip of any distance. The mechanic who packed my bearings is well aware of the torque spec and I was standing there when he did the work.

That leaves me puzzled as to why those two lugs galled when the remaining 4 were just fine.

There is no published spec for my new Sendel wheels. I torqued them to 90 fp.
__________________
John W. Irwin
2018 Interstate GT, "Sabre-Dog V"
WBCCI #9632
Pahaska is offline   Reply With Quote
Old 07-11-2013, 10:56 PM   #518
Rivet Master
 
Steve Bryant's Avatar

 
1991 34' Limited
Wichita , Kansas
Join Date: Nov 2008
Posts: 817
Images: 7
John,
I always like to take an acid brush and brush some graphite-based anti-seize compound on lug nuts. As a matter of fact, I use the stuff on any engine or drive train assembly unless it is something that should have thread locking compound or a Teflon sealant (like engine head). Anything related to a marine engine (outboard or inboard) should have the anti-seize too.

You don't have to put it on the lug nuts every time, but every third time, wouldn't hurt. This will eliminate galling, rusting, seizing, etc. It will also ensure a more correct torque value.

Steve
Steve Bryant is offline   Reply With Quote
Old 07-11-2013, 11:23 PM   #519
2 Rivet Member
 
Thisisliving's Avatar
 
1972 31' Sovereign
Longview , Washington
Join Date: Dec 2012
Posts: 62
Images: 4
Has anybody used Les Schwab tires? In a LT 16?
Thisisliving is offline   Reply With Quote
Old 07-12-2013, 06:28 AM   #520
CapriRacer
 
CapriRacer's Avatar
 
I'm in the , US
Join Date: Sep 2012
Posts: 989
Quote:
Originally Posted by switz View Post
I installed Centramatics and the 15" Michelins on the 25FB International after getting it home. That trailer has a GVW of 7,300 pounds and a tongue weight loaded of 1,175 pounds. That means the trailer axles are supporting about 6,125 pounds. The 10% derated capacity of the four 15" Michelin LTX (P) 235/75R15 XL tires at 50psi is 7,932 pounds which is a substantial safety margin exceeding 25%.

We have now ordered a 2014 27FB Classic which has a GVW of 9,000 pounds and perhaps will have a 1,100 pound tongue weight. For conversation purposes, the axles would be supporting about 7,900 pounds. Thus the 15" Michelins would have no safety margin if the trailer were fully loaded.

That means that I will order five Michelin LT 225/75R16RE M/S2 tires with SenDel T03-66655T wheels just like Airstream will install on the Eddie Bauer models or install on a trailer at the factory. The four 16" Michelin tires have a load capacity of 10,720 pounds at 80psi. That means we have a load safety factor exceeding 35%.

I selected the M/S2 over the XPS Rib for the wet braking characteristics and the Green X rating on the tire.
I just want to point out that there is side to side and front to rear variation in the loads on tires. It's the worst case that is important.

Caution, your safety factor might not be as large as you think.
CapriRacer is offline   Reply With Quote
Reply

Tags
16" tires, ltx


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
15" to 16" Wheels/Tires on 2007 Safari Rollertoaster Tires 53 01-23-2011 06:41 AM
Wheels and Tires shepherd57 Argosy Motorhomes 7 08-09-2010 07:14 PM
16" 5 on 5 1/2 wheels - What tires? Benjo Tires 10 02-15-2010 07:41 PM
New wheels and tires upgrade to 16" & Michelin Tin Diesel Wheels, Hubs & Bearings 9 04-23-2008 10:48 AM
Wheels and Tires Fordstream Tires 4 01-12-2006 09:51 PM


Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by the Airstream, Inc. or any of its affiliates. Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.



All times are GMT -6. The time now is 08:40 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.