Flat spot on tyres

[Mike Costigan]

I suspect tyres of the 1970s were made from rather different compounds to more recent tyres. Back then the popular tyre here was the Avon Triple Duty sidecar tyre - there are plenty from the 1970s still giving good service, whereas the identical tyre from more recent manufacture develops sidewall cracks within five or six years.

[Mogens]

Thank you all , For the various comments, Anyway I have not given up jet .The mentioned tyres are not the slightest cracked or worn (the but and fins from cast is still present)  I have warmed the flat spots with a hair dryer to 45C .Most flat spots was reduced  to 1,5mm ,then I used one /two clamps and two pieces of plate to put force on sides of tyres.
I have 5 Avon triple duty sidecar tyres  also produced in 2007,but they have never been mounted or out of living room,bought for an other car .  The car will in future be an axelstands if not out for a drive. 
Mogens

[Tony Press]

An interesting experiment to try and prove the tyre experts wrong with their five  to ten years. 

I suspect that the tyre walls would be approaching solid and the tread would have little grip.

I know the current trend is to ignore expert opinion and believe facebook and twitter but I think tyre safety is important even on an Austin Seven.

[Steve kay]

Tony, ignoring "expert opinion" is one thing, ignoring years of experience and collected millions of road miles is something else.

[Ian McGowan]

Personal experience has, for me, reinforced the view of the tyre experts. When I bought my chummy it was on 5 Avon Triple duty 19x3.50 tyres - still with reasonable tread left, which I measured and noted. 8000 miles later I again checked the tread depth - no discernible wear at all. I decided to investigate these amazing tyres further; non of the tyres had a DOT code which made them at least 20 years or so old. They were very inflexible and I had never been happy with the road holding so, following the experts advice I bit the bullet and ordered 5 Longstone 3 stud tyres and 5 innertubes to match.
     Glossing over the usual wrestling match removing the old tyres, these new tyres totally transformed the handling (and wet weather braking) of the car. The old Avon tyres were more like concrete than rubber!! I will never drive on tyres over 10 years old again.

[Alan]

Talking about tyre age is misleading because it’s only part of the equation. Conditions of use are at least as important. A tyre which is kept outside in the sun and used only occasionally will have a completely different life expectancy to one which is used every day and kept in a dark garage in between. This is the reason the tyre industry is reluctant to see a life requirement introduced on car tyres. If asked is a 5 year old tyre ok to use I’d say I don’t know it depends. If asked about a tyre made in the 1990s I’d say almost certainly not.

[Steve Jones]

......non of the tyres had a DOT code which made them at least 20 years or so old. 

Now you've done it, Ian! Given that I bought those Avons, I've been trying to work out when I bought them. I can remember where they came from and I can remember them being fitted but when? Must have been late 1990's but I can't pin it down any more accurately. 

Steve

[Tony Press]

Tony, ignoring "expert opinion" is one thing, ignoring years of experience and collected millions of road miles is something else.

My grandfather lived to 98 - smoked all his life !