For what its worth- Tires

[Max Hubrich]

Just finished a 1000 mile trip today.

Since I have had two blowouts (Michelins) on my right side inner dual in the last year, I decided to monitor the pressure and temperature on all my tires closely with the TST sensor system I have installed on the Coach and the toad.

I was not surprised to see the RR inner tire running 5-10 degrees hotter and 10 PSI higher than the other 5 coach tires as they heated up with road use. That tire was within one pound of the other three on the rear axle when they were cold and they all had the same temperatures, +/- two degrees at the start of each day.

My conclusion of this minor research "project" is exactly what another member of this forum said a while ago. He said an 'ole tire man told him years ago, when he had a blowout, "I'll bet it's on the inner right rear dual and your running Michelins!!" For some reason that wheel position gets more of a work load than the others do.

So therefor, I recommend the best THREE TIRES you own, or have mounted, should always be on the STEER wheels and the RIGHT REAR inner dual .

Anyone else out there running a TST system that can confirm my "project" results?

[I've got to update my picture- We lost our old dear friend and traveling buddie, Jessie (our 14 year old Lab), a week ago to natural causes (cancer)-- it hurts so badly].

[denochs]

Max, so sorry for your loss. It sounds like he was just as close as a family member. We get close to our pets and enjoy their company.

Thanks too for the info on the tires. A couple of questions for you. Does your study conclude that we should run less air pressure on those inside tires? If so, how much. Also, since we have a tag axle, would that make a difference?

Dave

[Flossy]

Max, I thought it was an anomaly with our rig but our TST monitor shows the RR inner at about 10 degrees and PSI higher than the others also.

Dave

[speed racer]

Quote:

Originally Posted by Flossy Max, I thought it was an anomaly with our rig but our TST monitor shows the RR inner at about 10 degrees and PSI higher than the others also. Dave

If you have a tire that is overheating it is eather over loaded or under inflated. In a case where duals are concerned I have seen that people put two tires that don't have the same tread wear and the tire with the most tread carrys the majority of the load and overheats.

[paz]

I have an infrared temperature sensor that I use to check tire temperatures whenever we make a rest stop. The inner duals almost always run 10 degrees higher than the outer. This is because the inner tires get less ventilation and air flow.

It seems that the inner dual fails more often than the outer. IMO, a frequent cause of this is because many people don't bother to check the inner duals (or don't get an accurate pressure check) because the inner duals are hard to reach.

[H. Miller]

Quote:

Originally Posted by paz It seems that the inner dual fails more often than the outer. IMO, a frequent cause of this is because many people don't bother to check the inner duals (or don't get an accurate pressure check) because the inner duals are hard to reach.

Which only means that everyone should have a good TPMS

[Gary RVRoamer]

I'm with Paz - it is "normal" for the inner dual to run hotter due to restricted ventilation, and that in turn causes it to increase in psi, which might then cause it to carry a bit more than its share of the dual load.

But why would the right tire be hotter than the left? The sunny side may run hotter than the shady side and sometimes a road that turns predominantly one way will stress the tires on that side a bit more, but why just the inside right rear?

One explanation I have seen is that a crowned road will cause an uneven load on duals, but it was never clear to me how that could effect just the right inner. Any thoughts?

[mythplaced]

Max,

Well wishing thoughts your way. So sorry for you.

[John H...]

Max, Unrelated to your tire issue, just want to offer you condolances on your loss. Our Benji is 15 years old and we hate to think about what will inevitably happen some time. He has been traveling with us since he was a pup. John H...

[J Walker]

I can't give an answer from direct observation, but 5-10 degrees temperature increase doesn't yield a 10 psi pressure increase. If it did there would be a lot more tire problems. In the case of duals, having one dual 10 psi higher than the other would lead to excessive tire wear and possibly a blowout. Might the TST sensor be wrong?

[paz]

Quote:

Originally Posted by RV Roamer [Gary] I'm with Paz - it is "normal" for the inner dual to run hotter due to restricted ventilation, and that in turn causes it to increase in psi, which might then cause it to carry a bit more than its share of the dual load. But why would the right tire be hotter than the left? The sunny side may run hotter than the shady side and sometimes a road that turns predominantly one way will stress the tires on that side a bit more, but why just the inside right rear? One explanation I have seen is that a crowned road will cause an uneven load on duals, but it was never clear to me how that could effect just the right inner. Any thoughts?

Another theory is because the right outside dual is the one that is most likely to drop off the edge of the pavement on a narrow road causing the inside dual to carry all the load. I'm not too sure about that because it's hard to imagine a momentary extra load would cause that much of a problem. Zipper failures are caused by longer-term overloading/under inflation.

[Max Hubrich]

Good points--

I'm going to inflate the right rear outer dual to 10 PSI higher (cold) than the RR inner so when the tires warm up from road use they will be running the same pressures. That should make them wear evenly through out their work day.

I have another 1000 mile trip coming up shortly for our annual migration to Maine for the summer. I'll report on the success (hopefully not a failure) of this logic.

Here are the pictures of the most recent failure of my RR inner blowout. The tire had 4000 miles on it. It occured at 6:30 am, just slowing down to exit the I-10 interstate in Gulfport MS. The sun was not a factor as we were driving from 12:30 am, at an average of 60 mph. It was in early November, ambient temperature about 50 degrees.
The tire was born in mid '07. Michelin replaced that tire (at no cost) with a new one. I also bought another one, so that side of the axle has two mated, brand new tires.










Thanks to everyone about our "Jessie". She loved every person she met. She was "Family" to us.

[RedT]

Not an expert, but just my own speculation based on experience and what an old OTR trucker told me - many people 'ride' the white line, and many road surfaces edge off at or just beyond the white line. If your outer dual is on the white line, the inner is taking more than it's share of the load. That uneven load, plus the lack of cooling air on the inner dual will cause heat build-up.

RedT in Glendale, AZ
'04 Meridian
'03 Jeep Liberty
M&G Brake System

[dieselclacker]

Quote:

Originally Posted by RV Roamer [Gary] I'm with Paz - it is "normal" for the inner dual to run hotter due to restricted ventilation, and that in turn causes it to increase in psi, which might then cause it to carry a bit more than its share of the dual load. But why would the right tire be hotter than the left? The sunny side may run hotter than the shady side and sometimes a road that turns predominantly one way will stress the tires on that side a bit more, but why just the inside right rear? One explanation I have seen is that a crowned road will cause an uneven load on duals, but it was never clear to me how that could effect just the right inner. Any thoughts?

Could it be a combination of crowned road, and a hotter running inside dual caused by less air circulation, plus being right next to brake assembly. This would cause over inflation of the inside tire, which would cause it to carry more than its share of the load. A crowned road would, tend to shift weight of load to inside tire as stated in earlier post above.

I think if I had such an on going problem, I would go with a higher load rated tire, and short of that, I would try what Max is proposing, that being running about 10 PSI more air in outside dual, hoping that they would equalize in pressure once they reach operating temperature. Worth a try anyway.

Dieselclacker