If they're in bad shape, the car's ability to accelerate, stop, and turn in all conditions is greatly compromised.Everybody knows to replace tires when the tread gets down to the wear bar, but what about when they get too old?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.
This is brought about when UV light oxidises the rubber causing it to dry out.
For instance, the tire seen above has a code of DOT DA08 JM1R 3011, which would indicate a tire manufactured in the 30th week of 2011.
DOT R5HG FHR 404 would indicate a tire manufactured in the 40th week of 1994 (or 1984, or '74).
Of course, this aging is highly dependent on where the tires live.
Tires in hot dry climates have much shorter lives than those in moderate, moist climates.