[DeTomaso] old tires

[Charles McCall]

I had a set of Pirelli P7R's, in 345-35-15 flavor, split wide open on me in
less than 30 miles. 

Brand new tires (un-used), with gorgeous treads and the little rubber nipple
things but they split right down the middle. I repeat - they had 30 miles on
them when they failed.

They were also 12 years old. I was lucky and was going about 25mph when I
heard a "BANG!!!!!!". I pulled over to see what the noise was and noticed
the car sagging to one side. 

15" tires are hard to find and can be expensive. 

Massive body work on your car, or extensive surgery on you because your tire
blew out in the first curve can be even more expensive. 

After first-hand experience with a quality tire that blew out on me, I won't
run old tires again, regardless of how nice and new the treads look...

Charles McCall
1985 DeTomaso Pantera GT5-S #9375
"Raising Pantera Awareness Across Europe"
http://www.poca.com/index.php/gallery/?g2_itemId=2323
-----Mensaje original-----
De: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] En
nombre de JDeRyke at aol.com
Enviado el: domingo, 18 de abril de 2010 20:59
Para: rtaspl at aol.com
CC: DeTomaso at realbig.com
Asunto: Re: [DeTomaso] old tires

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!)
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