According to this piece on ABC news, the rubber compound in tires dries out over time and becomes brittle after 6 years or so.
This can lead to blowouts, nasty rollovers and to the premature pushing up of the the old daisies!
While tyres contain anti-oxidising chemicals which significantly slow down the rate of ageing, this wax-like substance is only released when the tyre is in motion.
Therefore, if the tyre is not used frequently or is stored away ineffectively, they will age more quickly rendering them unroadworthy when returned to use.
Also, different tires can dramatically affect the way the bike handles.
Additionally, some tires are designed to slide earlier to warn the rider they are approaching the tires' limits.
Many riders really like this feel while for others the sensation of sliding the bike around is terrifying and will instantly destroy any confidence.
The first two digits of the code represent the week of production during the year (from 1 to 52) while the second two digits represent the year of manufacture.
In this example, the manufacture date code is 1413 - where 14 denotes the week of manufacture and 13 represents the year, meaning the tyre manufacture date was the 14th week of 2013.
Low mileage, older cars tend to be most at risk from premature ageing - as drivers assume the tyres are still in good condition if they have plenty of tread.