What do you need to know about the age of your tyres?

Birthday cake??

most people do not know that the date of manufacturer is stamped on sidewall of a tyre ...a fact i only found out about when i had a problem ..cracks in sidewalls ..when i bought the car it had new tyres fitted all round ..12 months later it failed the mot ..cracked sidewalls!!..the car was two years old when i bought it ...the tyres ..were made 8 years before the car!......lesson?  check your sidewalls

Many car companies recommend replacement of Tyres that are 6 years old and anyone using Tyres 10 years old is an accident waiting to happen

On My Motorcycle i change any tyre that is 6 years old no matter how much tread there is on the Tyre

As the rubber compounds within a tire ages, they become less pliable/flexible.  This means the tire will offer less grip.

The rubber compounds can also dry out, leading to what is sometimes called 'dry rot'.  This leads to cracking in the rubber which may lead to leaks and possibly even a blow-out.  A blow-out while driving can be dangerous, even fatal.

Most tire experts state tires tires should be replaced 6-8 years after manufacture, regardless of remaining tread depth.

Nothing, really. As long as they still confirm to the relevant laws about tread depth, the age of a tire is really irrelevant. 

I am not sure what you are asking, but tire age effects wear, just getting older degrades tires even if not used, and being exposed to sunlight even degrades them faster.