What's the life span of tires?

[swordsman]

What's the life span of our tires? I know we want to keep them until they're totally useless or like those jeepney drivers who seem to have a competition on who has the most 'kalbo' tires. But for safety reasons, especially when travelling along SCLEX, NLEX, SLEX, Star Tollway at high speeds, what's the manufaturer's recommended tire replacement period?

There's the wear and tear factor, even if the tire looks to be just out of the dealership. I have mine for around 4 years already, though it still has around 75% tread.

[Type 100]

You ought to consider replacing your tires when they reach 6 years of age from manufacture date, regardless of how minimal the treadwear is on them. Rubber ages even when not used, and the UV radiation of the sun can accelerate their aging, so don't count on storing the tires somewhere to prolong their lifespan.

The manufacture date of a tire should be stamped on the sidewall as a four-digit code. For example:

"4008"

The first two digits refer to the week of the year, in this case the 40th week.
The last two digits refer to the year of the current century, in this case 2008.
So for this example the tire was manufactured on the 40th week of 2008 - and you have until the 40th week of 2014 before you should worry about tire replacement.