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Topic: Rubber, XZA2s, FMCA Advantage (Read 700 times) previous topic - next topic
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Rubber, XZA2s, FMCA Advantage

Yahoo Message Number: 78563
Hi,

I wanted to pass along some thoughts relating to tires.

Rubber, if not specially formulated with a U/V stabilizing compound, will deteriorate when exposed to the sun. That said, you might think about tire wear as both mechanical and chemical. Mechanical wear refers to rubber being abraded from the tread by running it on a rough surface. Visual inspection of the tread gives a good idea of its condition. Chemical wear refers to the breakdown of the rubber compound by exposure to the elements. Direct sunlight usually being the most damaging. This isn't as easy to identify especially in the early stages. In the later stages cracks in the rubber usually appear.

On commercial vehicles that are driven constantly, road wear is the most degrading factor. For example, tires in commercial service seeing 400 miles per day 5 days per week log 2,000 miles per month. At that rate they would hit 50,000 miles in just over 2 years (25 months). Even the most basic of rubber compounds would last 2 years and I doubt any tire manufacture would spend the time to formulate special compounds to extend rubber life beyond what's economically feasible. The "take away" here is those using commercial tires (Michelin XZA2s for example) need to watch sun exposure carefully to ensure they get maximum life from their tires. Use whatever methods are available to keep the tires out of direct sunlight. According to several tire dealers I've spoken with Michelin commercial tires don't score particularly well on the sun rot index.

Our vehicles, driven for recreational purposes, usually fall well below the mileage logged by true commercial driving. That means sun rot is more likely what will kill your tires. As a general rule and a conservative safety practice it's a good idea to dump your tires after 5 years. I'm sure many of us here have seen tires with serviceable tread life get pitched into the recycle bin. That's not to say 7 year old tires aren't safe. But high pressure tires exposed to the sun for that length of time are a risky proposition. Blowouts on large high pressure tires are a real bad scene.

Yesterday I just dumped the last of my G670 RV Goodyear tires with a date code of 2005. At about 32,000 miles they had lots of good tread left on them. My concern was, of course, sun rot. Those tires (#7 and #8 off the tag axle) looked perfectly fine and I might have gotten another year or two out of them. I just wasn't prepared to continue facing the increased possibility of a sidewall blowout. You have enough on your mind whilst driving a big heavy vehicle so worrying about blowouts doesn't need to (and shouldn't) become part of your driving experience.

Our bus now has Michelin XZA2 Energy tires 295/80R/22.5" in 8 places. I haven't up to this point used tire covers but I'm planning on it from this point forward. Concerns about tire sun rot are greater with the Michelin tires. The tires seem fine, drive well and support the vehicle with expected inflation pressures. I haven't run them long enough to provide any feedback. Initial impressions are good, however.

This go around I used the Michelin Advantage Program. The tire cost quoted to me was $638/ea through the program. I changed them myself which is a pain in the *ss. The FMCA Advantage Program basically lets you buy the tires directly from Michelin at or near wholesale cost. The dealer makes their money from a delivery reimbursement from Michelin. Tire sales through this program aren't as lucrative for the dealer but most are happy to put some bread in the cash register and move on. It helps keep their inventory moving. The final CC bill hasn't hit yet and I'm expecting to see taxes, recycling charge, etc. I'll report back with an exact price when I find out. At this point that price is HUGELY better than the $850 I paid last season and the $750 the season before. FMCA was right on their game when I called for information. The overall process was straight forward and the folks I dealt with were knowledgeable, helpful and courteous. Not all dealers participate in this program. I worked with Jack's Tire and Oil in SLC, UT.

Safe travels to everyone!

Best - Scott

2006 Allure 430 #31349
(Bus-Stead Lemon)

Re: Rubber, XZA2s, FMCA Advantage

Reply #1 –
Yahoo Message Number: 78571
Scott,

400 miles a day would be 2,000 miles a week, not a month, and you accumulate 208,000 miles in a two year period, not 50,000. But I get the point.
Kevin Burns

2000 Affinity #5865

Re: Rubber, XZA2s, FMCA Advantage

Reply #2 –
Yahoo Message Number: 78575
Kevin - Thanks for pointing out the error. Need to be more careful with the math. 2,000 miles per week means 50,000 in 25 weeks. It suggests even less attention would be paid to U/V stabilizing compounds if tires are expected to last only between 6 months and 1 year. Sorry for the mistake and I'm glad the gist of the article came through in spite of it.

At 09:43 PM 4/14/2012, you wrote:

Re: Rubber, XZA2s, FMCA Advantage

Reply #3 –
Yahoo Message Number: 78577
Scott

My understanding is that there is another factor to tire life. I have been told by several Michelin dealers (when I asked about the use of tire covers) that the biggest factor in life of an RV tire is inflation and driving it down the road. They have said that preservative compounds in the rubber come to the surface when the tire flexes as it rolls down the road and if the RV is not being driven then those compounds do not come to the surface and therefore protect the tire. The general advice has been to use covers if you are not regularly driving the RV. Also, they did not seem to put much stock in Goodyears claim that it has a special sun protection compound in their tires. These were Michelin dealers so who knows. A similar issue comes up when I talk to manufacturing techs about UV Protection in RV waxes. Some advertise that their wax has special UV inhibitors and others say that all premium waxes now days have UV additives. Who knows?
Changing those tires must have cut into your skiing time? Maybe you changed the tires when it was too dark to ski.

Dan 2006 Allure 31348

Re: Rubber, XZA2s, FMCA Advantage

Reply #4 –
Yahoo Message Number: 78581
Dan - Thanks for the informative comments and it's always good to hear from a close sibling. I'm glad this thread motivated a few to come forward with their knowledge and experience. It's all very helpful.
That's very interesting about solid solution U/V compounds in tire rubber. I know the chemistry behind rubber is extremely complex and high tech. In our case (last three seasons) we have driven about 800 miles per year so the covers are a good idea. And I think for those driving more miles, covers couldn't hurt any. This fall we may find ourselves traveling around more than in previous seasons. That's why I wanted to get the tire situation under control. As Michelin says, "There's so much riding on your tires." And this couldn't be more true for those of us rolling our house around on America's highways. It's time to give the cold winters a break and seek the warmer climates. Change is good.
I think Michelin makes a pretty good tire. That said, it's important to know a little bit about how tires are made, what factors influence their wear and what needs to be done to extend their life. After all bus tires aren't cheap so it makes sense to get the most from your purchase. Proper care isn't expensive either. Same can be said for getting an education in tires.
As for Goodyear tires, we retired the last of our G670 RV skins a couple of days ago. I was glad to see them hit the recycle dump. Perhaps they end up in a highway compound or generate some electricity. As for Goodyear's claims I can't say I have any insight. I seem to remember their new G670 model blowing out spontaneously owing to some issues with construction. Not sure if that had anything to do with rubber formulation, belting or both. Many had accidents and incurred financial damages. My details are sketchy and perhaps someone will jump in on this that has the straight dope on what happened.
My experience with Chuck Schwab last season was horrific with getting my tires changed. They were an over priced shop and the last straw was some kid heading for the undercarriage with a hydraulic bottle jack and no idea where the lift points were. Luckily I headed this disaster off by forcing my way into the shop and immediately putting a stop to it all. As it turned out I didn't have the lug wrench for taking off the inner wheels. Somehow we got it all sorted out. It shouldn't have come down as it did, however. Jeannie and I did the front tires without a hitch and also the tags just a couple of days ago. Now I find out the smart tire sensors are wrong so I'm in the middle of getting that fiasco sorted out. Murphy said, "If a job goes smoothly, you've overlooked something." Murphy is my hero and a true genius and optimist.
We had our last day of skiing this past Thursday and it was pretty good considering the overall season was way light on snow and good conditions. Over the past three season we did about 1.5 million vertical feet in 1800 miles of sliding. Time for a break. Looking forward to Spring and some warm weather. For us there are more things to do in warm weather like this: http://muniac.smugmug.com/photos/swfpopup.mg?AlbumID=22111074&AlbumKey=3qfGHs It's good to be able to move around. Take care.

At 09:57 AM 4/15/2012, you wrote: