Dear Bree,

Taking a closer look at my tires the other day, I noticed that there are a lot of numbers and letters and symbols printed on them.  Some of them, I’m familiar with, but I have no idea what the others mean.  Can you translate?

Mandi in Arkansas

Hi Mandi!

I can absolutely help you translate those letters, numbers and symbols!  I’m going to pick a fairly common tire size and explain, then we’ll hit on some common symbols.

Tire sizes are written like this: P265/70R17  121R.  The numbers before the slash are a measurement (in millimeters) of the distance across the widest part of the tire, called the section width.  The letter that comes before the numbers usually signifies the type of vehicle the tire is for; for example, P stands for passenger car, LT stands for light truck and T stands for temporary (spare).

The numbers after the slash (in this case, 70), is the aspect ratio, or profile, of the sidewall.  It indicates that the height of the sidewall is 70% of the tire’s width.  Lower numbers = shorter sidewalls.

That R you see after the 70 means that this tire has a radial construction.  Other letters you might see there would be B (belted) and D for bias-ply tires.

The 17 tells you the width of the wheel on which the tire should be mounted.  This could be a whole number (like 17) or it could be in half-inch increments, like 16.5.  Generally, the number is given in inches, but in some cases, you might see measurements in millimeters.

Now, for the service description.  The 121R sequence tells us the tire’s maximum load rating or the amount of weight the tire can bear (in kilograms; in this case 121), and the R gives us the speed rating, or how fast the tire can safely rotate.  The lowest rating (speed) that you’d usually see on a passenger car is Q, which is equivalent to 99 mph.  Y is the highest rating at 186 mph, but if you see it enclosed in parenthesis ((121Y), for example), that means that tire can go over 186 mph.

If you keep looking around your tire, you’ll see the letters DOT with a series of numbers and letters after it.  Every tire has a Dept. of Transportation (DOT) label that can tell you the factory of the manufacturer (the first two letters).  The next six characters are manufacturer specific code to track the tire (in case of a recall, for example), and the last four digits give the date of production (weeks out of 52 first, then the year).

You can also learn the tread wear, traction, and temperature ratings.

Other letters and symbols can indicate if a tire has a specific weather rating.  M+S, for example, means that the tire’s tread has been designed in a way to better handle in the mud and snow.  A snowflake and mountain symbol means that a tire has met the minimum performance requirements for driving in snow.

Hope this answers some of your questions, Mandi. All of the information given right on a tire can help you choose the best tires for your specific vehicle and driving habits.  If you’re not sure exactly what you need, or you think you want something different than what you’ve got, come in and see us at one of our RNR locations!  We can answer all of your questions!  We can even set you up on a payment plan to fit your budget and get you back on the road quickly!  Hope to see you soon!

Stay safe!

Bree