[Healeys] Tyre life expectancy

[Guy R Day]

Michelin will suggest a thorough inspection on an annual basis after 5 
years, and dispose of after 10.
The question is one of the 'how long is a piece of string' ones.  There are 
so many variables with tyre construction or types, the use it has over the 
1000 miles and the storage conditions for the rest of the year.  If the tyre 
is stored with the weight of the vehicle on it, the tyre may keep the 
'bulge' at the bottom, if at a slightly low pressure it probably will. If 
kept at a high pressure to reduce the bulb it may promote cracks.  Jacking 
up may help.  UV from sunlight will degrade the carcase, ozone produced from 
nearby electric welding will do the same.  Soft compound tyres will harden 
and harder ones may become brittle.  Internal delaminating from standing may 
not be visible from the outside and some 'blow outs'  (instantaneous 
decompression) are caused by this problem.
Today's tyre construction is a very high tech affair and even alterations in 
building humidity affect internal tyre bonding processes.  Some makes I will 
not run on at all, some people won't run on a remould tyre but at least the 
carcase has been tested for thousands of miles beforehand!  Passenger 
aircraft all run on re-moulds with cargo planes getting the new, untested 
ones.  So that piece of string is .......... how long?

Guy R Day




----- Original Message ----- 
From: "Tom McCay - Classic-Car-World Ltd"
Sent: Thursday, May 27, 2010 11:29 AM
Subject: [Healeys] Tyre life expectancy


> Hi all, we had an interesting discussion last night at our monthly local 
> car
> club meeting when someone asked the question of "what life expectancy 
> should
> we expect from the tyres fitted to our classic cars"? Some of these cars 
> do
> less than 1000 miles a year and almost all are laid up during the winter
> months in dry storage. Some cars have been in the same ownership for over 
> 10
> years and have the same tyres fitted when they acquired the vehicle.
>
> The tyre condition is good with no apparent cracking on the tyre walls 
> that
> you see on some very old tyres and tyre wear is not the issue either, but 
> at
> what point should you consider changing these anyway due to age?
>
> Kindest Regards
>
> Tom
> Classic-Car-World Ltd
> www.ccw-tools.com
>
> AH 3000 MkIII (BJ8)
> MGA 1600
> Mini Park Lane
> _______________________________________________