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Old 04-02-2013, 02:33 PM   #1
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Consolidated Tire information

The weight/pressure chart was posted elsewhere but done so by me off topic and so hard to find.

So in one thread here is the Tire pressure/axle weight chart previously posted and new is a 24 page Michelin brochure with quite a bit of useful information.


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Attached Files
File Type: pdf LoadAndInflation.pdf (47.6 KB, 41 views)
File Type: pdf RVTiresBrochure.pdf (2.01 MB, 35 views)
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Old 04-02-2013, 03:13 PM   #2
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I have checked the list of Michelin and the smaller first mentioned tires are calculated with the 0.7 power in the universal formula, that is still used in America for C-load and up. What they do right , and that is how it is done in Europe, is that they make a seperate list for G and H load, and not as is done in America all the Load-kind letters in one list for the same sises.
The larger tires are calculated , so I checked , with the power of 0,8 in the universal formula. higher power leads to higher pressure for lower then maximum load. For larger tires a power of 0.9 would be saver ( so it gives for every pressure/loadcapacity the same deflection.
I searched once for a European list from Michelin, and there the larger tires where calculated with that 0,9 power, so stange that Michelin calculates different in America and Europe.
Comfronted them with that by mail, but they put it on small differences in sises and the lower used speeds in America.

I made my own formula wich is right for every kind of tire, and use it in my camperRV tyre pressure calculator , wich you can find in the next map.
https://skydrive.live.com/?cid=a526e...E092E6DC%21793
Also made a spreadsheet to make your own pressure/loadcapacity-list with my system. If you give the maximum load and load-kind ( G or H load fi) I can make a list for it the way you want, in PSI ,LBS and per axle or per tire and rounded the way you like.

Greatings from not a tire-specialist from Holland
Peter
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Old 04-02-2013, 03:30 PM   #3
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Great info! Thanks!
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Old 04-02-2013, 03:37 PM   #4
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I'm sooo confused I think I will just go to a tire professional and have them figure it out for me. Is there something I am missing by not going thru all these calculations if I have access to a good tire company in town?
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Old 04-02-2013, 04:40 PM   #5
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Quote:
Originally Posted by dalford View Post
I'm sooo confused Is there something I am missing ?
Only that softer pressure gives a better ride but can cause the tire to overheat and fail; higher pressure is a rough ride but not as likely to overheat.

In short you want the middle ground, the right pressure for the weight you are carrying. That's the idea of the reference material, weigh your coach and then select the correct pressure for your load. Best riding and handling with the least risk of overheating/failure.

The tricky part is finding the right pressure on the chart and then adjusting if you feel the chart is not correct (as per jadatis).

My coach has a card on the wall saying to inflate the tires to 90psi, but according to the loaded weight, I need only 70 psi, (much more comfortable ride). I split the difference and inflate to 80 psi.

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Old 04-03-2013, 11:53 AM   #6
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The goal of the formula's is to keep the deflection of the tire the same for every pressure/loadcapacity- combination, and so the same as for maximum load and reference-pressure on it ( as it is called in the official formula, furhtter Pr.
This Pr is lower then the maximum pressure of the tire and printed on the sidewall of C-load tires and up. On P-tires and XL only the maximum pressure is printed, and so the Pr is lower ( P-tires 2,4bar/35psi and XL 2,8bar/41psi).

What I am trying to make clear is that the in America used formula for C-load and up is giving more deflection when using on lower loads, or the other way around when calculating loadcapacity for lower pressure then Pr, as is done for making the lists.

most people rather look in a list then use my spreadsheet.
That is why I made my spreadsheet for making the lists.
Will see if I can make a simpler spreadsheet where I give such a list for the most used Loadindexes and for the different Load kinds ( C-load 50 psi , D-load 65 psi , E-80psi,F-95psi,G-110psi,H-120 psi.
Best is then to give it per tire otherwise I have to give to many lists for dual load also.

Advantage of looking in and making such lists is that the responcibility for picking the right loads is for the user and I can never be blamed for advicing to low pressure.
And that is the biggest risk, that you underestimate the actual load on the seperate tires.
Weighing is the only sure way, and then best on 4 points.
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Old 04-03-2013, 12:21 PM   #7
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hey mods, is this library worthy?
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Old 04-06-2013, 03:28 PM   #8
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I made the spreadsheet and made some PDFs with it .
It uses my own formula wich is even saver then the European calculation.
The loadcapacity for a sertain pressure is always lower then the European tyre makers calculate and to my opinion takes care that the deflection of the tire stays the same.
Also in red the loads that are calculated for higher then the maxloadpressure.
So you can look back in this list and the answers are always saver then any list given in the world.
But there are always chanches of doing wrong, thoug the calculation is close to ideal. If you yudge the actual load to low , or you read the tire-data wrong , or the pressure or load is measured inacurate, damage to the tire can still appear.

Edit: Attachments deleted as requested.
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Old 04-07-2013, 11:17 AM   #9
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I forgot something in the formula that I used for the PDFs I gave in my former post, so I Will ask the moderator to remove those documents and now give the good ones. The old ones game to to high loadcapacity, but I chached it in the spreadsheet that I used for it, so this new is OK.
Sorry
Attached Files
File Type: pdf PLC65PSIDload8ply.pdf (68.9 KB, 19 views)
File Type: pdf PLC80PSIEload10ply.pdf (69.0 KB, 14 views)
File Type: pdf PLC95PSIFload12ply.pdf (68.8 KB, 18 views)
File Type: pdf PLC110PSIGload14ply.pdf (68.9 KB, 15 views)
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Old 04-07-2013, 11:26 AM   #10
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Could only make 4 atachments so here the PDF's for 50 psi /Cload/6ply steps 2,5 psi ( mind the , instead of . wich we use in Holland for it) and 65psi/Dload/8ply with steps down of 3 psi.
120psi/H-load/16ply with 5 psi steps.
Again sorry for the mistake.
Attached Files
File Type: pdf PLC50PSICload6ply.pdf (69.1 KB, 21 views)
File Type: pdf PLC65PSIDload8ply3.pdf (68.8 KB, 19 views)
File Type: pdf PLC120PSIGload16ply.pdf (68.6 KB, 15 views)
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