How to Read Tire Size

Reading Tire Size

P225/70 R16 91S. P215/65 R15 95H. P225/50 R17 98H. Yeah, that’s right-tire sizes can be confusing!

Luckily, that’s why our service team here at Nissan of Mobile wrote this incredible guide on how to read tire sizes and understand what’s going on. Why did we write this article? Well, we did because we receive loads of questions from our customers in Mobile, Prichard, Saraland, and the rest of Alabama.

Now, without further ado, get ready to mind your Ps and Qs-and your Rs as well…

Tire Sizes: Your How-To Manual

To best way to explain how to read tire sizes, is to use an example: your standard P225/70 R16 91S tires.

  • P: Passenger Car Tire. This initial letter lets you know which class of tire you’re dealing with. For example, if you see LT at the beginning of the tire size, then it’s designed for a light truck.
  • 225: Section Width Tread (mm). That next number (right before the slash) is the distance on the tire from one sidewall to the other. They measure this distance in millimeters.
  • 70: Aspect Ratio. What does this mean? It’s the ratio of the height of the sidewall to the section width. For example, with a section width of 225 millimeters (see above) and an aspect ratio of 70, you’ve got a sidewall height of approximately 157.5 millimeters. See, that wasn’t so hard!
  • R: Radial Construction. This letter indicates which type of construction was used within the tire casing. R means radial, B means belted bias, and D means diagonal bias. Let us know if you have any questions, as our Nissan of Mobile team can explain terms like these in much more detail.
  • 16: Wheel Diameter. This is easy enough to understand, as everyone wants those huge rims!
  • 91: Load Index. Check out the final number to figure out exactly how much weight a given set of tires can handle. This is something to look into if you’re buying tires for a work vehicle, right?
  • S: Speed Rating. Check out the final letter to figure out exactly how fast you can safely drive on a given set of tires. Of course, don’t forget to always follow your local speed limit laws!

For another example, take P215/65 R15 95H tires. These are passenger tires with a section width tread of 215 millimeters and an aspect ratio of 65; the tire casing utilizes a radial construction, while the wheel diameter is 15 inches; finally, you’re working with 91 load index and an H speeding rating. Learning how to read tire size is a piece of cake!

Contact Us Today at Nissan of Mobile for an Extensive Tire Selection!

Here’s the bottom line: here at Nissan of Mobile, we have one of the best tire selections around Alabama. It doesn’t matter whether you’re in Saraland, Prichard, Mobile, or anywhere else in the state. We’ve got all the Ps, Qs, Rs, and more. Best of all, you finally know how to read tire size. Contact us!