Does lowering tire pressure make tires last longer when our trailers sit for months?

[Wayne]

@CapriRacer since you are willing to answer questions here (thank you very much for that!), I have another one for you.

We owned the Airstream for 3 years and each winter it was stored inside a heated building, up on blocks. I stored it on blocks so I could take the weight off the Dexter torsion axles. Dexter customer service did confirm the rubber in the torsion axles would last longer if the weights was removed.

Once the weight was off the axles and tires, I would let all but 10 psi out of the tires. The tires were Michellin LTX what I maintained 80 psi. I read that if the pressure was reduced in the tires, two things would happen.

1) The tire would last longer, because not as much oxygen would be forced into the rubber compound.
2) The reduced strain on the cords meant that the tires had less of a chance to break a cord while in use.

I always wanted to ask a tire engineer this question! Are either of the above points true?

Thanks!

 

[CapriRacer]

........ I read that if the pressure was reduced in the tires, two things would happen.

1) The tire would last longer, because not as much oxygen would be forced into the rubber compound.

That seems like a reasonable result, but is there evidence that this actually takes place? Surely with all the winter/summer tire changeovers, there must be a lot of confirmation that this is true.

But there isn't. Why??

I think it's because rubber degradation is very much temperature dependent. After all, there is the Arrhenius equation which states that chemical reactions double with every 10°C rise in temperature. I'm guessing that this overpowers any oxygen migration that might take place through the tire.

2) The reduced strain on the cords meant that the tires had less of a chance to break a cord while in use.

Again, is there any evidence of cord breakage in service? If I don't count road hazard related cord breakage, I don't think I've ever seen any.

If I try to understand why I don't see any cord breakage in service, I think I have to point to Fatigue Theory: Failures occur when the number of cycles exceed a certain value that is dependent on how much stress there is. Deflating a tire is a one-time event, but a tire experiences 10's of millions cycles. That one-time event doesn't have any effect on the end result!

Bottomline is that deflating a tire appears to be unnecessary.

 

[ls1mike]

My trailer is in covered building. I keep mine fully inflated, but change them every 3 years. I don't know if anything extra you are doing matters. Mine is a 2012 and I did have to replace an axle but that was due to the spindled getting galled up. Turns out the spindle itself was welding off just enough to side load the bearing from time to time.

 

[Wayne]

Again, is there any evidence of cord breakage in service? If I don't count road hazard related cord breakage, I don't think I've ever seen any.

Thank you for your answers!

I'm amazed at the strength of tires. If you calculate the surface area of the inside of a tire and multiply that by the air pressure, you can arrive at the absolute force applied to the tire from the air pressure. The calculation yields an astounding amount of force to the tire and to the wheel. It is amazing that a tire can be inflated for years and not burst. I guess that's why we have tire engineers!