Can you please explain the difference in the meaning and application of the following two tyre marks?
(1) 255/40 R17 94W and (2) 225/45 R17 91W I know the “R17” means it is a 17-inch rim, but what is the difference between 255/40 and 225/45 and what do 94W and 91W mean?
NOEL COETZER – By e-mail
The first number is the width of the tyre in millimetres and the second is the aspect ratio. This denotes the height of the tyre, measured from the rim, expressed as a percentage of the width.
For the first tyre, this means that height is 0,4 x 255 = 102 mm. The R means radial, then follows the diameter in inches.
The next number is load rating, in this case 670 kg, and W is a speed rating, in this case 270 km/h. The last two ratings are explained on a chart that can be seen at tyre dealers.
