Tires: Life Span of tires, sears auto center, michelin tires

Question
Hi John,
I'm wondering about the lifespan of tires.  I drive a 2000 Toyota Sienna minivan.  Memorial Day, 2006 my family and I were out of town enjoying the long weekend.  We picked up a spike in the right front tire, and had it replaced at a Walmart, the only store open on the holiday.  Ten days later we took the car to a local Sears Auto Center and had the remaining 3 tires replaced with new Michelin tires.  We added roadside service and the tires had a 50,000 mile warranty.  Today, I took it for an oil change and the serviceman noticed a leak in the Walmart tire.  When they checked the remaining tires, they all had cuts and wear on the rims and tread and indicated they all needed to be replaced.  They noted that the tires put on in June, 2006 were manufactured in 2000.  When I took it back to Sears to have the 3 tires under warranty replaced, they refused, saying they were worn out from being over-inflated.  I asked to see the manager.  He wasn't there, and when I came back within the hour to speak with him, first he told me there was no shelf life to tires. Is this true? He also noticed Armorall on my tires and said that wears out tires. (I wash my car maybe 4 times a year, so it definitely wasn't that)!  When I persisted, he agreed to give me a $30 credit on each tire, however I needed to pay labor, etc.  My question: Am I being unreasonable to expect them to replace the three tires at no charge?  From my point of view, he should never have put on 6 year-old tires.  I live in Phoenix, where the temperature is extreme.  I'm livid, as I have 3 kids and am constantly transporting them and their friends in this van.  I take car safety seriously and feel they should never have put on tires that old.  Any advice?

Answer
Yes and No.

Tires have no shelf life and it does not matter when the tires where made.  That has no effect on the tire in any way.
But it you want newer tires, check the last numbers of the DOT.  They tell you what week and year the tire was made.

Does over inflated or armorall void the warranty?  YES.  Any PSI over the recommended will void the warranty.  So the road harazd will not cover it, since it was not a 'road' harazd.  Any chemicals will void the warranty.  Read the book ( if you got one ) that came with the tire on what is not covered.

But it does not stop there.  There is more.

Was there a tire rotation?

Yes - If yes, then the shop should have checked the PSI and corrected it, making the shop required to cover the tires.
No - If no, then you voided the warranty and the road harazd.

But if the tires are one year old on the car, ( tire age is based on time on the car, not when it is made. ) then they should have covered the tires 100%.

I would recommend a BBB complaint for full replacement, minus labor for a 12 month old tire.

John