How long should tires last before they dry rot?

Harvard wrote:
I do not know anything about nitrogen in tires BUT I hear (from the TV) that wood/lumber kept under water and deprived of oxygen will last for many years. Maybe the nitrogen in a tire will displace the oxygen and reduces whatever oxygen does to encourage the rotting process.

Just to be clear, I got the nitrogen strictly for tire pressure stability. I have no idea whether it helps or hurts dry rotting, although I cannot see how it could affect the outside of the tires.

I do not know anything about nitrogen in tires BUT I hear (from the TV) that wood/lumber kept under water and deprived of oxygen will last for many years. Maybe the nitrogen in a tire will displace the oxygen and reduces whatever oxygen does to encourage the rotting process.

This goes back a lot of years to 1995, when I bought my first class C. It came on Michelin tires. Those tires were on that MH for slightly less than 50,000 miles, and slightly less than 10 years, when I replaced them, after getting two blow outs in a short period of time. The first blow out was on a tire that had a flat many years before and it was plugged, instead of being patched.
Those tires still had plenty of tread left. The main thing ( I think) that let them live that long was the fact the MH was used as a daily driver for those ten years. Back and forth to work or wherever for their whole life. This was also 10 years (or almost) in Florida.

We keep ours covered and use Aerospace 303 when we go out for a trip, going on 4years old, 10K miles look great.

Harvey51 wrote:

I thought the advantage with nitogren was for psi stability. Hot or cold it's the same. Am I right?

All gases follow the universal gas law PV= RT so nitrogen filled tires respond exactly the same way to temperature changes. There is a temperature/pressure affect when there is liquid water condensed in the tire and then it heats up and goes gaseous - this doesn't happen with nitrogen because water is removed completely in the process of seperating it from air by liquification.

Some say oxygen can find its way through the rubber slightly more easily so pressure may drop less over winter with nitrogen. If true, this also implies that oxygen will pass from the air outside into the tire with no oxygen so your nitrogen filled wheels may actually slightly increase in pressure over time.

More info here: http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=191

It called the "ideal gas law" because it only really estimates what might happen. While I can imagine a molecule or two of O2 from the air gettng into a tire, the oxygen (and air) will move towards a state of greater entropy. Maybe you are thinking of the gas constant? Under the ideal gas law, gasses of a different mole weight will behave differently. The law also does not consider things like leakage rates, moisture content, and the reactivity of the elements and compounds involved. Crunch the math on gasses at the proposed pressures and temps and you find it makes no difference anyway.

Pv=nrt often get brought into the N2 conversation, but it all it really shows is that all gasses are good at filling tires. Its the phase change of Condensable materials that can alter the pressures more radically. In other terms, things in there that turn to liquid or solids under reasonable temperatures are a bigger problem. H2O is one material that comes to mind.

Michelin tires seem prone to this problem. I have had two sets of tires replaced on my unit so far and it is only 8 years old. The problem is two-fold: Lack of regular use and exposure to sun. I am happy that Michelin is a respectable company. They have replaced both sets under warranty, prorated for treadwear. They covered 85% of the cost the first time and 65% the second time. I know the sun is a factor because the second time they only replaced the front tires and the outer duals. The inners were in good condition. They put the inners on the front axle and the 4 new ones went on the duals. As long as they continue to cover them I will continue to stick with Michelin. I bought replacement tires for my Dodge Dakota from Michelin because of the good customer support. I have been happy with the set on the truck. Our new Toyota Sienna has Michelins too.

I thought the advantage with nitogren was for psi stability. Hot or cold it's the same. Am I right?

All gases follow the universal gas law PV= RT so nitrogen filled tires respond exactly the same way to temperature changes. There is a temperature/pressure affect when there is liquid water condensed in the tire and then it heats up and goes gaseous - this doesn't happen with nitrogen because water is removed completely in the process of seperating it from air by liquification.

Some say oxygen can find its way through the rubber slightly more easily so pressure may drop less over winter with nitrogen. If true, this also implies that oxygen will pass from the air outside into the tire with no oxygen so your nitrogen filled wheels may actually slightly increase in pressure over time.

More info here: http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=191

Another advantage of nitrogen over air is the absence of oxygen in the mix, which can oxidize & rot the tire from the inside.

I replaced six Michelin tires a year ago after a number of years of non-use. Some were 4.5 years old some were 8 years old, all had enough sidewall cracks to be suspect. The Socal sun, summer temps, sitting mostly undriven and not using tire covers seems to shorten tire life considerably. Wish we could get some cold hard facts on RV tire life not confused by hearsay or brand loyalty.

bigcitypopo wrote:
I have heard that Aerospace 303 is good stuff, but I would also get some tire covers... and probably a coach cover as well.

I have an RV carport with full sides and closed rear coming, but they are 2-6 weeks out before then can set it up. Can't wait to get our beautiful rig under cover!