Broken Cord on Michelin Tire

[Hisham Amaral]

David I found this link to be very good at answering some of the question I had about trucktires. I would like to share it with the group. Please discard if it is an information overload. Hope that your trip to the West Coast was good and enjoyable, our was the best ever. We will meet at one of the riles some day soon. http://www.goodyear.com/truck/pdf/radial..._All_V.pdf Hisham & Sue Amaral 97 WLWB 43 W. Bloomfield, MI --- On Tue, 9/9/08, David Brady wrote: From: David Brady Subject: Re: [WanderlodgeForum] Re: Broken Cord on Michelin Tire To: WanderlodgeForum@yahoogroups.com Date: Tuesday, September 9, 2008, 1:39 PM Thanks Neil, that helps a great deal. Glad to see you here on this list. Just a couple of questions: 1) can I measure "deflection"? 2) does "deflection" change as the tire rotates at speed? 3) sounds like the sole purpose of tire pressure is to maintain the correct deflection? 4) if I were able to dynamically adjust runtime tire pressures, would optimum tire life/performance be achieved by maintaining the correct deflection under all ambient operating conditions? Thanks, David Brady '02 LXi, LV Neil & Pat wrote: > > * Hi Pete, David, Greg, Randy and all else who have been following > this thread. * You called for a tire engineer to make input into this > subject; well I have been doing that for 36 years now and also happen > to own and operate a Wanderlodge (PT-36 ) for the past 12 years and > have written extensively on the subject of RV safety in my book on the > subject as well as respond to many of the tire questions posed on this > and other forums. Perhaps I can help. > > The original question was re: a broken belt (actually shifted) on a > Michelin tire with the thought was this a problem on the Michelin > tires and would it be subject to warranty. At 27k miles the tire > problem in question is almost certainly the result of a “road hazard” > either a rock, shoulder drop off, hitting a curb or possibly even > improper usage of “chocks” for leveling or other purposes. Had it been > a manufacturing problem it would have shown up much before that time. > You did receive proper advice in that this is not a warrantable > condition by the manufacturer but often dealers do provide “road > hazard” protection as a service to their customers. > > This is one of the major differences between truck tires and those > used on automobiles; in order to carry heavy loads much higher > pressures are used and the tire is normally operated at a lower > deflection rating. On trucks the deflection of the sidewall when > normally inflated is on average 8% by design when it is properly > inflated for the load carried, in contrast on an automobile tire the > deflection is approximately 12%, thus, yielding a smoother ride and a > tire less susceptible to impact loads as mentioned above. For your > interest aviation tires actually operate at 32% deflection to carry > the immense loads involved but do so with a duty cycle limited to a > few seconds. The “hoop strength” of the belt package” is under immense > tension from the inflation of the tire becoming more and more rigid > and unyielding as pressure goes up making the tire much more critical > to this type of abuse. So for our RVs we have a quandary, RVs are the > only vehicles on the road, which operate at 100% of the capability > 100% of the time making their safe operation somewhat precarious. We > must carry the correct (high) amount of air pressure to carry the load > (at the correct deflection rate) but should not exceed that pressure > or operate below the required amount. Higher pressure than required > will yield decreased steering power, braking power, higher impact type > damage as well as decrease life; too low a pressure will result in > over deflection, hotter running temperatures (possibly destructive) , > poor handling, greatly reduced life and the potential for catastrophic > premature failure. Take your pick, but none of these options are very > appealing to me. > > The above realities of life is the reason why the tire manufacturers, > the RVSEF and myself all repeatedly attend and lecture at rallies and > anywhere RVers gather to spread the word that RVs are different and > incur considerably more operator responsibilities from the > owner/operators. It is absolutely essential that you have your RV > weighed properly wheel by wheel to assure that none are overloaded and > then and only then determine the correct pressure for your specific RV > under the conditions you operate it. Plain and simple there is no > other way. > > Always happy to be of assistance: > > */ Neil LeKander /* > > */ Author, The Rver’s Ultimate Survial Guide /* > > */ http://www.rvsafetyinfo. com /* > > less likely to crush to the wheel rim, possibly protecting the tire > from pinching damage, but the high pressure would also place the tire > under tension pressure ... so??? > > Any tire engineers out there? > > Pete Masterson > > > ------------------------------------------------------------------------ > > No virus found in this incoming message. > Checked by AVG. > Version: 7.5.524 / Virus Database: 270.6.17/1655 - Release Date: 9/5/2008 7:05 PM > -- No virus found in this outgoing message. Checked by AVG. Version: 7.5.524 / Virus Database: 270.6.17/1655 - Release Date: 9/5/2008 7:05 PM ------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/WanderlodgeForum/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/WanderlodgeForum/join (Yahoo! ID required) <*> To change settings via email: mailto:WanderlodgeForum-digest@yahoogroups.com mailto:WanderlodgeForum-fullfeatured@yahoogroups.com <*> To unsubscribe from this group, send an email to: WanderlodgeForum-unsubscribe@yahoogroups.com <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/