Tire Guy Was in A GOOD MOOD

[Melbo]

Ready to hit the road and I found that one of my tires has a sidewall leak.

It didn't seem like I was going to get any satisfaction til I talked to the right guy.

They looked it over -- talked to the recap guys --- and sent me to talk to the MAIN GUY

I had bought some low mile good tread take offs about a year ago.

He told me we don't warrant used tires (fair enough) we don't repair side wall damage (sounds reasonable) You have had the tires for over a year (yes I have)

I will sell you an 11R 22.5 XZE michelin brand new installed balanced out the door for 459.04 

Seemed reasonable to me (it was 2/32's bigger than the tire it was installed next to on the drives)

So I am ready to hit the road.

Melbo

[JohnEd]

I don't think you can mix diameters.  I always heard that you needed to have them matched cause one will try to roll at a different rpm than the other so the scrub and heat up.  Uneven diameter on fronts or tags/bogie.  But I ain't the tire guy around here or anywhere else for that matter.

Great price though.

John

[HB of CJ]

Can you put the new Michelin on the front and run one of your existing tires that more closely matches the other driver tire?  Or...you can have all 4 of your drive tires trued (shaved) sosss they all match exactly?

Reason being that over time and temp cycles the different running radius (diameter---revs per mile) MIGHT cause overheating and separation issues?  If it were mine, I MIGHT be concerned about the difference.  HB of CJ (old coot_

[babell2]

The overwhelming concern I would have is the weight distribution between the tires.  The smaller tire would not be "pulling its' weight" and putting more load on the larger tire.  That would generate more heat and stress on the new tire.  I read that if you have a tire failure with greater then " ..." weight load the surviving tire is considered to be damaged and not to be used.
Just my $0.02

Brice

[eagle19952]

Seemed reasonable to me (it was 2/32's bigger than the tire it was installed next to on the drives)

You guys crack me up 1/16 total difference is 1/32 on the top and 1/32 on the bottom thats about .029.....
If i was really worried I would run the bIG BIG tire 5lbs low on air.
And move my beer (4 cases) to the side of the bus with the BIG BIG tire.

[eddiepotts]

I am not a tire guy either but everybody gets a chance to spend their 2 cents here. I would think if you had a larger tire on one side on your drive axle one side would be turning faster and load your gears with the smaller tire trying to keep up. I would suggest install the new tire on your tag and the old matched tag to the drive. The independent spinning should not cause a major problem. You may get a little more edge wear on the smaller tire due to the axle not riding flat. I do not think it would be enough to notice over the 8ft distance. your only looking at quarter of a thousant per inch over the 96 inches. I was typing with you eagle. I think your exactly right.

[luvrbus]

That would be a big set of calibers to measure that lol I don't think Mel really gives a big rat's @$# about the 2/32 " he liked the price but here we go pole vaulting over a ant bed.
I wonder if 2 identical tires from the same manufacture are that close I don't think so on my trucks it always seemed like one was a little different in size but in 100 miles the wear pattern would look the same

good luck

[boxcarOkie]

I don't think Mel really gives a big rat's @$# about the 2/32 " he liked the price but here we go pole vaulting over a ant bed.
good luck

Last year when I re-skinned Daddy's Hobby I started to go back with Michelin's until I saw what they wanted for them, and believe me, it was about $210 a tire MORE than what he paid (which resulted in no sale).  

He did get a great deal.

BCO

[Chopper Scott]

If your pushing in the corner you may want to make sure that bigger tire is on the right rear. Maybe drop a 1/2 pound of air in the right front and put a little wedge in the left rear and diamond the corner. You'll be ok...

[boxcarOkie]

If your pushing in the corner you may want to make sure that bigger tire is on the right rear. Maybe drop a 1/2 pound of air in the right front and put a little wedge in the left rear and diamond the corner. You'll be ok...

But don't pit now .... we're eating ice cream!

BCO

[Melbo]

I would have posted sooner but the bus is leaning and the internet couldn't make it in the window. 

We've logged about a thousand miles.  Getting over 7 miles per gallon --- traveling about 55 - 60 MPH   the 486 rpm on the steers at 12R 22.5 ( yes 12 R on the steers -- 11R on the other 6 ) is a little fast on the speedo compared to the GPS.

The tires told the heat gun that they are just fine -- but just to be sure we are drinking all the beer.

Melbo

[eagle19952]

The tires told the heat gun that they are just fine -- but just to be sure we are drinking all the beer.

Well then I HOPE your black tank is on the BIG BIG  tire side....
No waterin the lilacs....

[niles500]

Eagle - If you were a "Hero member" you would know that it takes 4 cases of beer per 1/64 of tread depth to offset the tire radius difference - In other words 8 cases of beer in this situation - Melbo, being a seasoned veteran, knows to keep the beer drinkers "centered" over the drives - Now how do you account for the beer drinkers' relieving themselves in the driver side commode with a curb side black tank while descending the outside lane of the grapevine with the jakes on high? Can't wait to hear this answer 

[Melbo]

We are WAY east of the grapevine but did make it over Raton Pass and sadly no Jakes but the retarder (just recently set up) worked flawlessly -- Any excess beer will be shared while floating in the river using the inner tubes we took out of the tires.

HTH

YMMV

Melbo

[JohnEd]

Melbo,

I had heard for many many years that "you cannot mix tire diameters on a dual".  End of story.  I never faced that situation/choice so I went no further than the "end of story" part.   That is what i shared with you and for obvious reasons.  For me, and I suspect many others, the issue wasn't 2/32s so much as it was "different diameters" cause I have never heard a number.....just "different".

Well, "pole vaulting over an ant hill" and "Mel really gives a big rat's @$# about the 2/32" and "he liked the price" all struck me as Cavalier on a tire safety topic.  Maybe it's just me alone but I don't think so.  I called the local tire shop and put the question to them.  Spoke with two different reps and got the same information:  If you mix tire sizes the larger tire will carry a disproportionate share of the vehicle weight at that corner.  That unbalanced share will go up with the delta in diameters.  The immediate result is that the larger tire gets hotter and with sufficient delta the tire will "FAIL", cause thousands of dollars damage to the bus, probably do damage that will necessitate towing, possibly ruin the sister tire on the dual and possibly cause a dangerous traffic accident.  The secondary problem is with accelerated tire wear. In general, the advice from the experts was "don't do that".  But I dug a little and got a number that you will be happy with.  It seems there is a limit in variance with diameters on a dual and that variance is ONE QUARTER INCH.  Less than that is OK from a safety perspective. 

The tire rep.s told me that after mounting any new tire you should closely monitor temperatures and check at a more frequent interval for a few hundred miles.  I have made numerous calls, local and 800, and I can't get an answer to "what temp differential indicates a problem?" nor can any on them tell me what the safe operating temp is for a highway tire.  I'll leave that to one of you guys that wants to pick up this ball and has better contacts.

Now here is the rub:  Remember back in High School where we learned that the circumference of a circle could be figgured by multiplying the diameter by 3.14?  Seems a one inch variance in diameters would yield a 3.14 inch differential in diameters. Sooooo, every revolution that littler tire will scrub/slide 3.14 inches......but not for very long and it will not be cool about it and we all know the Fonz's posture on cool.  BOTH tires run hotter by some margin.  ANY variance in circumference will result in accelerated tire wear and for me the really big eye opener, I am monocular, was that the situation doesn't self correct.  I thought they would even out but the tire guy said "no they won't".  Nobody tried to sell me a tire shaving/diameter equalization service.  That might be worth looking into if only to get more miles from a set of tires if you ever expect to wear them out legal like and we mostly don't.

One of the really nice pieces of info I got from this seems to be that you can mix used tires of "close" diameters without risk so long as they are within 1/4 inch.

And if you have occasion to EVER need to measure the diameter of a truck tire us a measuring tape.  Don't go scouting around the tire shop looking for a "really big set of calipers".  Clifford said so.....LOL

Your turn to talk,


John