The speed rating is coded as a letter. In the image below it shows ‘H’. It relates to the max speed the tire is safely rated for, as shown in the chart below
Tires have load rating that specify whats the max weight the tire can handle safely. It’s a little tricky since the number on the tire doesn’t directly correlate to a weight. But lucky for you, we’ve put the conversion table right here:
The key takeaway when shopping for new replacement tires is to make sure the new tire load rating is at least equal to your factory specification tire. This ensures the tires are able to handle the load of your vehicle safely and consistently.
For trucks that may or may not have a dually rear axle (4 rear tires), there is a special case. These tires are branded with two load indexes. The first number indicates the load carrying capacity if the tire is installed on a truck with a single-wheel rear axle, and the second number applies when the tire is used in a dual rear application.
It might seem counter-intuitive that a tire is rated to carry less weight when working together in a dual pair – but the purpose is to build in additional reserve capacity in case one of the two tires fails. This allows for a safety factor in the event only one tire carries the load normally handled by two tires (dually rear axle)
M+S: Mud & Snow. These tires will provide traction in light snow, but you wouldn’t want to be caught in a blizzard with a set of M+S tires.
Mountain/Snowflake or ‘Alpine‘: These tires are approved for “severe snow service”
Knowing what those numbers and symbols on your tires mean, keeps you informed and safe! Plus you can be that person that drops random tire knowledge at dinner parties and earn some wisdom points 🙂