Tire/Tyre Aging -- When rubber becomes dangerous

Yesterday at work I was having a discussion with three of my workmates about tires in general. The subject came up of "the lifespan of a tire", how long should you keep driving on your tires? So I decided to research exactly what the experts say.
Many of us really don't realize how dangerous these older tires we may be driving on are. So how old does a tire or tyre (depending on your country of origin) have to be to be dangerous? The majority of rubber manufacturers tend to agree on a TEN year maximum from the date of manufacturing.

Here are various picture samples, where you may find the date and the way it is printed before going into more detail.




The trick to finding the date most of the time is to look for the word DOT and follow that line along. Remember first two digits are the week of production XX out of 52, and the second two digits are the last digits of the year, such as 2007.
The tire in the last image above was manufactured on week 9 in the year 2007.

Here is picture of a tire that was used way past it's day, stay safe.

" The U.S. National Highway Traffic Safety Administration (NHTSA) and tire manufacturers are currently studying the many variables. Exposure to the elements (sun and atmospheric), regularity of use (frequent or only occasional) and the quality of care (maintaining proper inflation pressure, wheel alignment, etc.) will all influence the answer. So while tire life depends on the service conditions and the environment in which they operate, the difficult task remains how to identify all of the variables that influence a tire's calendar age and attempt to quantify their influence."
"The British Rubber Manufacturers Association (BRMA) recommended practice issued June, 2001, states "BRMA members strongly recommend that unused tyres should not be put into service if they are over six years old and that all tyres should be replaced ten years from the date of their manufacture.""
"More recently, The Japan Automobile Tire Manufacturers Association (JATMA) recommended practice issued May, 2005, states "customers are encouraged to have their vehicle tires promptly inspected after five years of use to determine if the tires can continue to be used (recommends spare tires be inspected as well). Furthermore, even when the tires look usable, it is recommended that all tires (including spare tires) that were made more than ten years ago be replaced with new tires."

Full articles on tire aging by tirerack.com, part 1 and 2:
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=138
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=183
All pictures from Google images.