Hi Reid,
I use a tire durometer to measure tread hardness. It measures from zero
to 100 on the "Shore A Scale". Tires range from around 50 for sticky
race tires to maybe 85 for hard commercial tires.
I have a spare set of 10 year old tires & wheels that came with my car.
These tires are nearly new as far as tread wear is concerned. The
measure nearly 90 on the Shore A Scale. Traction with these tires is
minimal, especally in the wet. On dry pavement they squeal loudly when
cornering & let loose easily.
I assume that you have already read about age hardening of rubber, it's
effects on traction, & the tendency to become brittle with the attendent
probability of tread separation on radial tires. A very real concern.
Much has been written on the subject. In effect, tires are hardened to a
desired level by vulcanization when they are manufactured. This
hardening process continues throughout the life of the tire, albeit at a
lower rate. The rate of hardening is subject to several variables such
as heat & UV light exposure, but six to ten years is a reasonable
estimate for useful traction & safety life.
I replaced the old tires with a new set of Michelin's that measured 70
on the Shore A Scale. The increase in traction was remarkable. I later
replaced these tires with a set of Gillette tires that measured around
65 Shore A. Even better wet & dry traction. The change from 90 to 70 is
a very large percentage of the 50 to 90 range.
The softer treads will give a bit less wear life but in my case the
tires reach old age before the tread is worn out.
IMO, tires are too cheap to sacrifice traction & possibly safety by
running on age hardened tires. Old "bias ply" tire designs may not have
the age related tread separation problems that radials have but they
still harden & sacrifice traction.
If you don't drive the car hard enough to notice the traction
differences & are not worried about tread separation, the 15 year old
tires may well be OK. My "joy rides" consist of pushing the car to it's
limits as it was designed to do.
Regards,
Dave Russell
BN2
Reid Trummel wrote:
> Hi Team,
>
> Just looking for some "anecdotal evidence" and thought maybe you
> could help...
>
> Over the decades I've read articles warning about the dangers of old
> tires, and yet I can't recall hearing of any actual problems with
> them. Some say you should not drive on tires more than 10 years old,
> or more than six years old, and tire sellers and quite happy to sell
> you a new set every year -- for safety's sake, of course!).
>
> I do not doubt that for high-performance applications, such as for
> racing, it is always better to have the best and newest of
> everything, but for the occasional joy ride -- the way that most of
> us typically use our Healeys -- it seems like overkill, at least
> based on my experience and the lack of evidence to the contrary that
> I have seen or heard.
>
> So my request is this: Please tell me if you have had any problems
> with tires that are attributable to the age of the tire(s). If you
> got a flat tire by running over a nail, the age of the tire isn't NOT
> the proximate cause of the flat -- I'm looking for stories of
> problems that were caused by, or the direct result of, the tires
> being old. No old wives's tales or "I heard of a guy who..."
> stories, please. YOUR personal, first-hand experiences, please.
>
> Anyone? Thanks.
>
> Reid Fearlessly driving on 15-year-old Pirelli radials
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