JBarca wrote:
I have 2 tire issues that just surfaced today. Since we have the tire tech folks here see if you can point me in the right direction of the problem. I do not yet have a blow out and I'm trying to keep it that way. ......
- Axle weight scaled at 7,660# with no water. When I fill the fresh tank over the front axle it adds 266 # more axle load.
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- Tire DOT date is 2908. Tires installed 3-28-09
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- I have weighed the left and right side of the camper. The slide side (left) is approx 350 # heavier.
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OK thoughts? Something is not right with this tire and my gut tells me get ride of it now, put the unused spare (bought same time) on and buy a new tire for the spare. It will be a Maxxis ST as Denman is no longer.
I would like to learn what went wrong or what I did to cause this.
I have my own tire machine and will demount the tire for inside inspection when the new spare comes in.
Thanks
John
I'll post the 2nd question in the next reply. It has to do with cracks in the other tires.
John,
I think you have a "rubber to steel cord adhesion failure" - kind of rare. Cause? Kind of hard to do at a distance. The cuts MIGHT have something to do with it, but we would need to connect the cuts to localized areas of separation.
The only thing that bothers me about this diagnosis - aside from not being able to see the tire in person - is that normally, steel belt adehsion failures also result in the tread being distorted relative to the casing - kind of twisted look. Does this tire have nylon cap plies? (Look at the sidewall and see what it says for construction)
My advice would be to replace all the tires unless you can definitively connect the cuts with the separation.
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I am also going to take issue with your math - AND EVERYONE PAY ATTENTION!! I have seen others do this type of math and I think there is a hidden pot hole there.
The principle is that for tire loading you want the absolute WORST loading. The load an individual tire experiences is NOT the average. Tires don't average out the load and neither should you.
First you said the axle loads were 7660, but added that the water tank adds 266# more axle load. Why didn't you add that to the axle loads? Why did you use the 7660# for your calculation as is when you already know the side to side loading is different? What about the front to rear loading difference?
OK, so I'm going divide the axle loading by 4 to get 1915#. Add 133# for the water = 2048. I estimate that there is a 15% variation in loading by wheel position, so the worst case is 2409# - and I recommend a 15% reserve, so the tire should be capable of 2834#
That mean an ST225/75R15 Load Range D is about 12% under that value.
I'd recommend going up to a Load Range E and 80 psi as the inflation pressure.
