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Kuhmo Changeout Saga


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#1 mickey

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Posted 12 July 2007 - 03:33 AM

Hi All ~ Well I finally rolled over and decided that I needed to have the feeling of not thinking when pieces of tire would fly. I checked locally and found that even some Kuhmo dealers are not certified to handle their truck type tires and could not get the 857's. ?? Long made short,Tire Rack beat the best local pricing by about $50. I ordered at 12:30 on Monday and they were plopped all wrapped and strapped in front of the barn at 1:45 Tuesday. On the news Tuesday evening,sadly a man was crushed to death while changing a rear tire on a bus. When I began to pull the Marathons off Eggster,the NAVIGATOR due to the news report brought out the red flags. I was asked things like : Can that skinny little jack safely lift the trailer? How far under the trailer must you go? How old is that jack? What else can you put under there to help? Can't someone stronger do this ? Why do you need new tires anyhow,the ones it came with still look brand new. Unless the NAVIGATOR is happy I can't be happy. Sooo, after a good 4 ton jack and a 6000# rated jackstand under each side,and a proven safety factor of almost 5:1 the green flag was waved. The tires were changed at the local tire/alignment shop. Metal valve stems were installed.He claimed that tires carrying more than 50# should have metal. He said he believed that the chinese wheels were good for the pressure.I asked about running at a pressure lower than 65#. Answer~ D rated tires run at 65#. He sees a lot of trailer wheels. I wanted to do this job without any shop tools,just as I would have to do on the road. What I first found was that my brand new 4 ton jack carried behind the seat of the pickup was all out of fluid.The fluid was sloshing around in the jack carrying case. No problem,I had a tiny funnel used to fill up the Coleman lantern and back in went the fluid [strained of course]. I did break down and go for the torque wrench to finalize the lugs,now that I do not carry on the road. I noticed that I had to jack up a few strokes worth to get the Kumhos on the axle,they are a bit taller not much. Just because a lot of you folks are curious and I am in that group I weighed a Kuhmo. It weighed 27#1oz. The marathons have about 7000 miles on them so comparison is not possible. Well,thats my story and I am happy ,the Navigator is happy it is over and the Eggster is gliding in a safer pattern because of it. Regards, Mickey

#2 Bobinyelm

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Posted 12 July 2007 - 06:53 AM

QUOTE (mickey @ Jul 12 2007, 06:33 AM) <{POST_SNAPBACK}>
Hi All ~ Well I finally rolled over and decided that I needed to have the feeling of not thinking when pieces of tire would fly. I checked locally and found that even some Kuhmo dealers are not certified to handle their truck type tires and could not get the 857's. ??

They are referring to BIG truck tires that use a separate rim that bolts on, and which retains the tire. A special cage is required to air these tires after mounting, since if the rim gives way, the energy can kill. We are talking tractor-trailer sized truck/commercial tires here, not little 14" car-sized truck tires on one-piece rims.

Long made short,Tire Rack beat the best local pricing by about $50. I ordered at 12:30 on Monday and they were plopped all wrapped and strapped in front of the barn at 1:45 Tuesday.


Good folks and good prices at Tire Rack!

On the news Tuesday evening,sadly a man was crushed to death while changing a rear tire on a bus. When I began to pull the Marathons off Eggster,the NAVIGATOR due to the news report brought out the red flags. I was asked things like : Can that skinny little jack safely lift the trailer?

Sure, based on the weight rating of the jack, but even jacks CAN fail, which is why jack stands are a good idea.

How far under the trailer must you go?

You don't go under the trailer AT ALL to change a tire. If you do (for whatever reason) you use jack stands.

How old is that jack?

WHo cares as long as it is good condition. A steel jack stored in a rust-free environment doesn't age. If it were made from cheese (or Scotch whiskey), it would age, of course. Hydraulic jacks DO age, of course, with seals liable to failure with age.

What else can you put under there to help?

Said Jack Stand, of course!

Why do you need new tires anyhow,the ones it came with still look brand new.

Like cheese and Scotch age, so does rubber, but unlike them, they don't improve with age.


Unless the NAVIGATOR is happy I can't be happy. Sooo, after a good 4 ton jack and a 6000# rated jackstand under each side,and a proven safety factor of almost 5:1 the green flag was waved. The tires were changed at the local tire/alignment shop. Metal valve stems were installed.He claimed that tires carrying more than 50# should have metal. He said he believed that the chinese wheels were good for the pressure.I asked about running at a pressure lower than 65#. Answer~ D rated tires run at 65#.

Your tire man is poorly informed (as a tire expert), though he has a good point about the valve stems, though many vehicles with Load Range E tires (80psi max) come with all-rubber valve stems.

Load Range D (or "C" or "E") run the the pressure appropriate for the WEIGHT CARRIED or the posted sidewall pressure, whichever is lower. There is no reason to run full pressure at max pressure when carrying less than maximum rated weight, and several reasons why NOT to run full pressure below the maxium weight. If you consult any truck manual, or with a tire engineer (as I did when I spoke with one of Kumho's tire application engineers), you will see that commercial tires (especially) recommend pressures that match the weight on that axle so that the tire will present a full contact patch to the road.


Well,thats my story and I am happy ,the Navigator is happy it is over and the Eggster is gliding in a safer pattern because of it. Regards, Mickey


Mickey,

Glad to hear that things went well, and there is a happy ending to the story.

I do urge you to contact Kumho and work your way to their engineering department. I no longer have the name of the engineer I spoke with, but your Casita might get a better ride, and your tires may achieve more even wear, at a slightly lower pressure (close to 50-55psi according to the engineer). There is no "danger" running 65psi, but beside a slightly stiffer ride, your tires will wear prematurely in the center of the tread.

Regards,
Bob

Edited by Bobinyelm, 12 July 2007 - 06:59 AM.


#3 micasita_17

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Posted 12 July 2007 - 08:57 AM

QUOTE (mickey @ Jul 12 2007, 03:33 AM) <{POST_SNAPBACK}>
I checked locally and found that even some Kuhmo dealers are not certified to handle their truck type tires and could not get the 857's. ??


I love it. Tires so strange even their own dealers are prevented from intsalling them!

Paula
Paula and Dennis
2000 Casita 17SD
Waco, Texas

#4 LSChilders

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Posted 12 July 2007 - 09:02 AM

I run 55 lbs of air in my Kuhmo 857s. (17ft, LD)

After pulling from KY to San Antonio, TX. and back, .... then to Indianapolis and back, ..... the tires show NO wear. The little mold nipples are still visable on the surface of the tread, ... all the way around, on both tires.

I love these tires.
Larry Childers #1251 (Hillbilly, 1st Class, At your Service)
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#5 garand1947

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Posted 12 July 2007 - 11:44 AM

...runs home to let 5 lb out of his tires smile.gif
Dave & Deborah
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#6 BlackDogs

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Posted 12 July 2007 - 11:59 AM

Actually, for those of us running ST tires, it is recommended that the tires be run at the maximum rated pressure regardless of the load. See the attachment. I think that this is way that ST rated tires are designed.

Attached Files



#7 Bobinyelm

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Posted 12 July 2007 - 02:09 PM

QUOTE (BlackDogs @ Jul 12 2007, 02:59 PM) <{POST_SNAPBACK}>
Actually, for those of us running ST tires, it is recommended that the tires be run at the maximum rated pressure regardless of the load. See the attachment. I think that this is way that ST rated tires are designed.


Yep, ST tires have their own set of rules, especially that when not towing, it says raise them
off the ground and reduce the pressure in them.
Much shorter life span both in mileage and calendar time, too (if one follows the guidelines).

Bob

Edited by Bobinyelm, 12 July 2007 - 02:11 PM.


#8 Rand

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Posted 12 July 2007 - 03:59 PM

Well shucks Bob,

Lift the darn tires off the ground and lower the pressure? Just got my new Kumho spare mounted today...worry about lifting the Casita up and lowering the pressure...too much else to worry about in this world...guess I better order some more and tote them around on the roof of the Casita...will kinda look like home :-).

Rand in the boonies:-)
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#9 Bobinyelm

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Posted 12 July 2007 - 04:07 PM

NO need to do that w/ Kumhos anyway!

It's NOT an ST tire.

Bob

#10 mjones12

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Posted 13 July 2007 - 02:50 PM

Someone told me that if I put the Khumos on my original Casita wheels, I could only inflate them to 50 pounds, even though the maximum for those tires is 65. I would like to hear more thoughts on this, as I am planning eventually to make the change and hoping not to have to buy new wheels.

#11 Bobinyelm

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Posted 13 July 2007 - 03:09 PM

This has been addressed many, many times, both on this forum and the "other" one.

You might do a search and decide for yourself what you wish to do if your wheels are so-marked. Not all are so-marked.

Kumho also says it is completely unnecessary to inflate them to 65psi for use on Casita (also posted several times), but if you really want to do this despite their guidance, a thorough search may help you make a decision you are happy with.

Bob

#12 Joe Z

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Posted 13 July 2007 - 06:05 PM

Got my Kumho's today anim_bannana.gif ........
New Wheels due wednesday biggrin.gif
Life is Good! smile.gif

Joe & Linda
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#13 cdsmith

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Posted 14 November 2010 - 04:15 PM

First Khumo failed on 2010-11-13 - date code 2007-07 - 25,673 miles.

It must be time to get new tires.
Joyce and Charlie Smith, Princess Lily, Rose, and Violet - Grand Prairie, TX
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#14 Chris Z

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Posted 15 November 2010 - 06:05 AM

Installed 195 Khumos in May 2008 on my stock wheels of the 2005 17' Casita. I run them about 62 psi and have almost 14,000 miles on them so far and they look great.
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