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07-14-2010, 07:34 PM
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#57
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Senior Member
Solo Rvers Club Workhorse Chassis Owner
Join Date: Jun 2010
Location: S. Texas
Posts: 272
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Quote:
Originally Posted by JManatee
well there you go, Never below recommended pressure but ok above.
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I don't see any clear objective statement on what "recommended" means... and I don't think you'll ever get their lawyers to allow the tire makers to provide it either.
Quote:
So the adding of a few PSI above the recommended helps with temperature change and slight loss of air over night.
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I didn't read those statements to mean that.
on the whole.. it is clear as mud.
If I'm reading and interpreting the transcribed statements correctly...
minimum psi = the weight based calculation of the rig relative to the tire characteristics (clearly stated on the sidewall) and *in conjunction with* what restrictions the wheel will have (stamped into the metal)
maximum psi = the psi as it is stated on the sidewall...
regardless of whatever voodoo someone may be using elsewise
obsessiveness = worrying over minor variations in gauge accuracy or daily temperature or altitude changes
common sense = KISS and to do whatever you do in a consistent manner
__________________
Bryan. 2000 Georgie Boy Pursuit.
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07-19-2010, 10:55 AM
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#58
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Senior Member
Winnebago Owners Club Ford Super Duty Owner
Join Date: Mar 2009
Posts: 1,129
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Quote:
USE the tire manufacturers inflation tables for your specific tire and weight. There really is no other bona-fide choice and it really can't be any easier.
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Wouldn't using the coach manufacturer's plated weight/tire size/inflation be a bona-fied choice presuming you know you are not overloaded?
Any easier? It isn't easy to get to a weigh station at your maximum load, unless it is on your way, it is open, you have as many passengers as you will ever carry, your food pantries are stocked, coach is full of gas and LP and your water, black and grey tanks are as full as you ever expect them to be and so on and so on. I have never found myself in the situation to get weighed at maximum weight, so I stick with the 80 psi Winnebago calculated when they put the DOT required placard in my coach. And I have a gut feel that I don't exceed the carrying capacity that is also on the placard in the closet.
__________________
Ole and Anne Anderson, Highland, Michigan
'02 Adventurer 32V, Ford F-53, ours since 4/08,Hankooks, Konis, SeeLevel, CHF
'84 CJ-7 , 5.3 Chevy, 3" lift, 33's, Detroit Locker, Fiberglas tub, winch, hi-lift
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07-19-2010, 12:18 PM
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#59
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Moderator Emeritus
Join Date: Jan 2007
Location: Litchfield Park, Arizona
Posts: 10,530
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Quote:
Originally Posted by CJ7ole
Wouldn't using the coach manufacturer's plated weight/tire size/inflation be a bona-fied choice presuming you know you are not overloaded?
Any easier? It isn't easy to get to a weigh station at your maximum load, unless it is on your way, it is open, you have as many passengers as you will ever carry, your food pantries are stocked, coach is full of gas and LP and your water, black and grey tanks are as full as you ever expect them to be and so on and so on. I have never found myself in the situation to get weighed at maximum weight, so I stick with the 80 psi Winnebago calculated when they put the DOT required placard in my coach. And I have a gut feel that I don't exceed the carrying capacity that is also on the placard in the closet.
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That's exactly the approach I used on my coach's maiden voyage... and @ 110lbs it nearly knocked the fillings out of my teeth. After getting weighed, the charts indicated that I could/should be at 85 all around. I went to 90 and it works well for me.
__________________
Rick, Nancy, Peanut & Lola our Westie Dogs & Bailey the Sheltie.
2007 Itasca Ellipse 40FD
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07-19-2010, 01:02 PM
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#60
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Administrator in Memoriam
Newmar Owners Club Retired Fire Service RVer's Spartan Chassis
Join Date: May 2000
Location: Newark, DE
Posts: 25,898
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If you don't know the weights, then inflating to maximum pressure is the safest way to go, but you could be putting up with a much harsher ride than necessary.
__________________
Adios, Dirk - '84 Real Lite Truck Camper, '86 Wilderness Cimarron TT, previously 4 years as a fulltimer in a '07 DSDP
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07-19-2010, 01:03 PM
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#61
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Senior Member
Winnebago Owners Club Ford Super Duty Owner
Join Date: Mar 2009
Posts: 1,129
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Quote:
That's exactly the approach I used on my coach's maiden voyage... and @ 110lbs it nearly knocked the fillings out of my teeth. After getting weighed, the charts indicated that I could/should be at 85 all around. I went to 90 and it works well for me
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I suppose that if my placard said 110 psi on tires rated for 110 psi, I too might go to more effort to weigh at a load that I would never expect to exceed, but already being 30 psi under my tire's rated pressure, my coach rides fine, especially with the Koni's that don't make expansion joints feel like speed bumps.
I will say that when I had two new tires replaced, the shop inflated them to 110 psi, after telling them I wanted 80 psi, and the ride was much harsher. Dropped the pressure back and all was fine.
__________________
Ole and Anne Anderson, Highland, Michigan
'02 Adventurer 32V, Ford F-53, ours since 4/08,Hankooks, Konis, SeeLevel, CHF
'84 CJ-7 , 5.3 Chevy, 3" lift, 33's, Detroit Locker, Fiberglas tub, winch, hi-lift
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07-19-2010, 06:36 PM
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#62
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Junior Member
Join Date: Jun 2010
Posts: 6
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when driving in the southwest during summertime ,towing across the desert, the road temps can get up to 170 degrees.now if your tires are not inflated close to max presuse you are asking for trouble.heat is the enemy of the tire.the lower the air presure the higher the friction to the tire.my coach rides just fine at max air presure and handles alot better.not too mention a little more pease of mind.just my opnion for what its worth.
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07-19-2010, 07:30 PM
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#63
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Moderator Emeritus
Join Date: Jan 2007
Location: Litchfield Park, Arizona
Posts: 10,530
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Quote:
Originally Posted by rdchevelle
when driving in the southwest during summertime ,towing across the desert, the road temps can get up to 170 degrees.now if your tires are not inflated close to max presuse you are asking for trouble.heat is the enemy of the tire.the lower the air presure the higher the friction to the tire.my coach rides just fine at max air presure and handles alot better.not too mention a little more pease of mind.just my opnion for what its worth.
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Hi rdchevelle... I think I know what you're saying. We too spend a lot of the summer bouncing between Phoenix, Palm Springs and San Diego. Are you making the point that the hot road surface will cause your tires to inflate to/above their max pressure even though they were below that temp when "cold"? Or, is your point that when driving in very hot weather we should begin with our tires inflated to their max?
__________________
Rick, Nancy, Peanut & Lola our Westie Dogs & Bailey the Sheltie.
2007 Itasca Ellipse 40FD
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07-19-2010, 08:16 PM
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#64
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Senior Member
Damon Owners Club Workhorse Chassis Owner
Join Date: Mar 2009
Posts: 24,024
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Quote:
Originally Posted by mudpuppy
I wonder how many blowouts are due to under inflated tires by folks looking for a Cadillac ride from a truck chassis.
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You remember the Ford "Roll-a-matics" (Explorers that rolled over too easily) a few years back... They blamed the Firestone tires.
My somewhat trained and experienced opinion is that you hit it on the head.
You see, Ford told owners to run 'em five pounds BELOW what Firestone said they should run. Add to that "new tires, I don't need to check the pressure" and an oil change tech at the last service interval who was too rushed and forgot the tire pressure and instead of 5 psi low you are running,, if you are lucky, 5 psi.
Now add one of Michigan (And many other states) More famous highway features {Voice of Doom Mode} THE POT HOLE {/Voice of Doom Mode} and ... Well... the rim goes straight through the side wall, causing sudden and explosive side wall seperation.. At this point Mr. Yuppie, who is not a vehicle operator, he's a point and shoot driver, Stands on the brakes with both feet (#1 thing on the DO NOT DO THIS list) and... that's all she rolled.
So the answer is MANY
Oh, what should you do when a tire blows? Well, when the tire blows it's a bit late to click the link... but. Click it now
Michelin North America RV Videos and Demos Page
__________________
Home is where I park it!
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07-19-2010, 08:35 PM
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#65
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Senior Member
Winnebago Owners Club
Join Date: Oct 2009
Posts: 1,170
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Road test results...
Quote:
Originally Posted by azloafer
The link that follows explains yet another way to check for proper PSI in your tires. I tried it and found that I needed to up the pressure on all 6 tires by 10 pounds. I drove about a half mile for this test. Added air and waited for cool tires and then tested again and they checked out fine. Joe
Optimizing Tire Pressure
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I neglected to mention that the air pressure I ended up with was 105 in all tires. I used the large sticks of chalk that is sold as kid's sidewalk chalk. It makes a nice wide chalk line. Happy travels, Joe
__________________
2008 Itasca Latitude 39W. Cummins ISB 6.7 Turbo 340HP. Allison 6 Speed. Freightliner XCS. Michelin XRV 255/80R 22.5 LRG. SuperSteer MCU. Safe-T-Plus.
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07-19-2010, 08:51 PM
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#66
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Senior Member
Join Date: Aug 2006
Posts: 799
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At a Spartan rally I attended a Michelin seminar given by two engineers from Michelin. After the seminar I sat at a table with them and I spread out my motorhome's corner weights and the Michelin chart. The two engineers and I discussed the tire pressures I should run and both engineers told me to add 5 psi to the chart. That is what I had been doing for years and it is what I still do.
My present trip proves it is a good idea to add 5 psi. I started the trip in the deep south and it was 90 degrees the morning I left and when I inflated my tires. As I have driven north the morning temperatures have dropped and now I am only 2 psi over the chart's psi.
If I had set the tires' psi exactly to the Michelin chart I would have to add 1-2 psi to all six tires every morning to keep them at the chart's recommendation due to cooler weather. Since Michelin says to never run under inflated I would be keeping busy inflating and that would be a PITA. By starting out 5 psi over the chart I can run from Florida to Canada and never worry about adding a couple of psi, or releasing a couple of psi every day.
By the way, I run a tire monitor system so I check the pressures from the drivers seat.
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07-20-2010, 09:53 AM
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#67
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Senior Member
Join Date: Jul 2005
Location: Cheshire County, NH
Posts: 223
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More is always better, right?
__________________
2008 Monaco Cayman XL 38PBD
Twenty years from now you'll be more disappointed by the things you didn't do than by things you did. Explore, Dream, Discover. Mark Twain
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07-20-2010, 09:53 AM
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#68
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Senior Member
Winnebago Owners Club
Join Date: Dec 2009
Location: Las Vegas, NV
Posts: 841
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RickO; do you remember your corner weights? Also, do you have the washer/dryer combo?
Two weeks ago in Phoenix (113 degrees) the battery charger shut off and the batteries were overheated. Never had the auto-shutoff come on before.
Anyway, if you still have them, weights please. (ours weighed heavier)
Thanks, Kerry
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07-20-2010, 10:40 PM
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#69
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Senior Member
Texas Boomers Club Freightliner Owners Club
Join Date: Mar 2004
Location: DFW Area, TX
Posts: 2,040
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Quote:
Originally Posted by JManatee
More is always better, right?
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No.
But in a dynamic environment (changing carried weight, changing altitude, changing temperature), not being a slave to a fixed way of dealing with it all makes sense, at least to me.
There are recommended daily amounts of vitamins, right? What happens if I get more than the recommendation? Do I die? One could argue that 20x the daily recommendation for Vitamin C is potentially not good for you. But no where in this discussion have we talked about excess like that? Most of the numbers are less than a 10% variance.
__________________
2000 Georgie Boy Landau 36' DP
2018 Equinox toad
KF5-NJY
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07-24-2010, 10:21 AM
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#70
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Senior Member
Commercial Member
Join Date: Mar 2010
Location: Akron, Ohio
Posts: 2,783
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RVDude
Yes the load formula is NOT linear as far as inflation effect is concerned.
Use the tables.
I think you will find that with very few exceptions the numbers are all the same, be they Bridgestone, Goodyear, Michelin or any other tire mfg.
The best is to get a copy of the table from your manufacture but the others will do untill you confirm with your manufacturer.
__________________
Retired Design & Quality Tire Eng. 40+ years experience. Recognized in the industry and in court as an expert in failed tire inspection as I have performed thousands of failed tire "autopsies".
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