Home WORLD How to Read a Tire Size & Understanding a Tire Sidewall

How to Read a Tire Size & Understanding a Tire Sidewall

Understanding the letters and numbers on your tire sidewall can be a bit confusing. Tak from Toyo Tires gives us some insight on how to read a tire size.His simple explanation addresses all the different specifications that are written on your vehicles tire. The sidewall of a tire contains a couple of key features:Let’s Take a Look for Instance at this Tire Size 255/35/R18 109V.

source/image: Autobytel

The “255” in the first part of the tire size represents the section width of the tire. The “35” represents the tires aspect ratio or height. The “R” stand for Radial in tire construction and the “18” stands for the wheel diameter in inches. The “109” is the load index and represents the tires maximum load capacity at maximum inflation pressure. The “V” represents the speed rating which is the max allotted speed of a tire./Autobytel

For those looking to get some advance knowledge about all the information a tire can present there is the DOT tire identification number (TIN).An example of a TIN would be DOT CX91 XX31309.The “CX” represents the factory code or where the tire was manufactured. The “91” represents the size code. The “XX3” represents the options code. The last four digits on the TIN represent the week and year when the tire was made. So for instance “1309” means the 13th week in the year 2009.


Another bit of information contained on a tire sidewall is the maximum load capacity. The max load displays a weight at a certain PSI. But this is not the recommended tire pressure that you should inflate your tires to. Instead follow the manufacturer recommended tire pressure setting as seen on the inside of a car’s door jam./Autobytel