QuestionUp until 2008 you recommended that tires would last 10 years. Since that time you stated "Recent bulletins from the tire industry indicate that tires degrade simply due to time. The age of a tire is important even if the tire is unused. There some disagreement over how to best express this age limitation, but my take is: If you live in a hot climate (AZ, CA, NV, TX, and FL) then the limit is six years. If you live in a cold climate (MN, ND, WI, MT, etc), then the limit is 10 years."
The RVIA also recommends this (I own an RV with 'good' tires that are 6 years old).
My question is: Is this accurate or a conspiracy on the part of tire manufacturers to sell more tires? Michelin's web site says: “While most tires will need replacement before they achieve 10 years, it is recommended that any tires in service 10 years or more from the date of manufacture, including spare tires, be replaced with new tires as a simple precaution even if such tires appear serviceable and even if they have not reached the legal wear limit.” For the first 100 years in tires, nobody said anything about tire age.
What's real, six years in FL or ten years?
AnswerAl,
John Baldwin published a paper entitled "Field Aging of Tires, Part II" in Oct 2004, (revised in Aug 2005), which directly answers your question. That paper shows a definite degradation in the rubber properties of tires over time. While he didn't address the heat history issue, I think all of us in the industry are aware that hot climates are worse for tires - and this is supported by a chemistry principle call the Arrehnious effect.
From all the research that was done as a result of the Ford / Firestone situation a few years ago, some things which were kind of known, but not well published, were presented as informational bulletins - and this area is one of them. In lawyer-speak, it's called "Failure to Warn".
One of the problems in trying to deal with the issue of climate is that the climate in Arizona is quite different than it is in Maine. Making blanket, all encompassing, statements is difficult - and different people are going to have different ways of trying to express this. The issue to quite complex and what might be true in Maine might not be true in Arizona (and vice versa). But it has been quite clear that if we wanted to point to the top 5 states where heat is an issue for tires, it would be (more or less in order) AZ, CA, TX, NV, and FL.
FL seems to be the odd man out in the list, but if you were to compare the average high temperature across a whole year for - say - Phoenix and Orlando, you would find that Phoenix has very high summer temps, and pretty low winter temps, while Orlando is pretty close to the same year round. When it comes to chemistry, high temperatures accelerate reactions, but moderate temperatures over a long period of time have the same effect.
So my recommendation of 6 years for Florida is based on the best information currently available.
