[DeTomaso] old tires

[JDeRyke at aol.com]

In a message dated 4/18/10 8:26:09 AM, michaelsavga at gmail.com writes:

> So the BIG question to the group is - are the (9 yr old) tires safe to 
> run over 100mph or is it a heat/time thing?
> 
Every case is different. I've run premium older tires well over100mph until 
cord shows. Others have had cheap near-new tires delaminate at 60 mph, 
causing body damage. Racing tires have no age-fighting chemicals in their 
compounds so they age faster. Its also where the tires spent most of their time. 
Ozone and sulfur gasses in the atmosphere attack rubber compounds and crack 
the sidewalls & treads, even inside garages. Time and high storage 
temperatures (or low inflation pressure that overheat the skins) also ages & drives 
out plasticizers from the rubber, making them harder and more prone to crack. 
Stored in downtown areas where there are many industrial pollutants floating 
around, tires might last a couple of years. A useful gauge is whether 
freshly-polished silverware turns black while you watch; the same pollutants 
cause silver-blackening.
Stored indoors, in quiet pollution-free rural areas away from factories or 
electric motors which generate ozone, tires   can last a good decade or 
more. A pro inspection will tell you more- and this will not likely come from a 
highschool dropout at the gas station who sells on commission. I'd take the 
mounted tires to someone who distributes race tires; he's likely more 
knowlegable and more interested in keeping you alive so you'll come back again.
Bottom line- its the same as a safety helmet; if you want to be perfectly 
safe, junk 'em every few years. If you're poor, get them pro-inspected before 
spending more time & hard-earned money. Pilotsports are getting scarce 
these days! 
My 2¢- J DeRyke (NOT a tire engineer, just a consumer. Use above at your 
own risk!)