From the size and tire type to the date when your tires were manufactured, there is a wealth of information in the numbers and symbols on your tire’s sidewall. Here is a breakdown of what they mean.
If a tire is marked with 235/55R17, this means:
- 235 is the width in millimetres from sidewall to sidewall.
- 55 is the aspect ratio, so this means the height is equal to 55% of the tire’s width.
- R stands for radial construction which refers to how the tires are made.
- 17 is the rim diameter in inches of the wheel from one end to the other.
Load Index & Speed Rating
Using the above example, you would also see ’99H’ on the tire sidewall.
- 99 represents the load index – a number that corresponds to the maximum weight a tire can support when properly inflated (for 99, the maximum weight is 775 kg).
- H is the speed rating that tells you the maximum service speed for a tire. This rating ranges from A – Z. Check with your Ford Dealer for more information about speed ratings.