Most Tyre Manufacturers honour warranties on their products for up to five years from date of manufacture.  

Regardless of how much tread is still left, it is recommended that tyres be replaced at around the age of 5 to 6 years. 

The fact is that rubber ages and breaks down.  Oxidants, ultra violet light and other factors cause tyres to deteriorate in ways that we cannot see with the naked eye.

Establishing the manufactured date of the tyre:-

Serial Number = 1602

means

16th week of 2002

National Road Traffic Act 1989 (Act 29 of 1989) 

No person shall operate on a public road - 

1. a motor vehicle, other than a tractor or trailer, which is equipped with a metal tyre;

2. a tractor or trailer, other than an animal-drawn vehicle, which is equipped with a metal tyre of less than 130 millimeters in width;

3. an animal-drawn vehicle which is equipped with a metal tyre less than 40 millimeters in width;

4. a vehicle which is equipped with a metal tyre unless the whole width of the tread of the tyre is at all times in direct contact with the surface of the road;

5. a vehicle which is equipped with a tyre which is in such a condition that it may cause or is likely to be a danger;

6. a motor vehicle which is equipped with a pneumatic tyre of which the rubber covering is worn or damaged that the fabric or cord used in the construction of such a tyre is exposed;

7. a motor vehicle of which a tyre is so constructed and fitted that the metal part of the wheel to which such a tyre is fitted may come into contact with the road surface;

8. a motorcycle which is equipped with a retreaded tyre;

9. a motor vehicle which is equipped with a regrooved tyre having a bead diameter of 430 millimeters or less;

10. a motor vehicle 

    1. which is fitted with a pneumatic tyre unless such a tyre displays throughout, across its breadth an around its entire circumference, a pattern which is clearly visible, and has a tread of at least one millimeter in depth; or

    2. which is fitted with a pneumatic tyre which contains a tyre tread depth indicator, if the tread is level with the tyre tread shall not apply in respect of a motorcycle with an engine which has a cylinder capacity not exceeding 50 cubic centimeters, or a trailer drawn by a tractor at a speed not exceeding 35km/h;

    [Subreg (j) substituted by cl. 42(a) of R.2116 of 05/10/2001]

11. a motorcycle with an engine having a cylinder capacity not exceeding 50 cubic centimeters, which is fitted with a pneumatic tyre which does not at any position on the tread thereof have a visible tread pattern over at least 80% of the full width of the tread;

12. a motorcycle which is equipped with a pneumatic tyre; which has a break in its fabric or which has a cut, measuring in any direction on the outside of the tyre and of such depth that it reaches the cords used in the construction of such tyre, in excess of 25 millimeter or 10% of the maximum width of the tyre, whichever is the greater; or

13. a motor vehicle which is equipped with a pneumatic tyre which has a lump or bulge caused by the separation of or a partial break in its structure.

Grooves are cut into the tread surface (by unskilled labourers) of an already smooth tyre, and more than likely a damaged casing.  In most instances, the casing itself has outlived its safe design period and has been subjected to the stresses and strains of bad roads.  Old tyres, generally discarded tyres or casings were found to be re-grooved.

Re-grooved tyres have been known to burst after less than 20km on the road.  Most have virtually no braking or effective road holding characteristics - yet they are regularly fitted to public transport vehicles such as minibus taxis.