Tire Sidewalls Explained

November 2nd, 2015
Tires in York, PAAt L & M Tire & Wheel, we occasionally hear customers asking about the information on tire sidewalls. There are actually quite a few designations on a tire sidewall, so let’s break it down a little. 
Take, for instance, a tire with a sidewall stamp of P255/55 R 15 97 T, a very typical tire for many vehicles. Here’s what that indicates: 
  • P – denotes a passenger tire. In other instances, LT stands for Light Truck, T for Temporary Spare, and ST for Special Trailer.
  • 255 – This is the “section width” of the tire, measured from sidewall to sidewall in millimeters. In the case of this tire, the width of the tread itself is 255 millimeters. 
  • 55 – This is aspect ratio, which means the height of the sidewall in proportion to the section width of the tread. In this case, the sidewall’s height is 55 percent of the 255-millimeter-wide tread. 
  • R – Radial construction
  • 15 – Designed to fit a 15” wheel
  • 97 – This is the load index designation, an indicator of the load a tire can carry safely. Load indexes range from 0 to 279, with passenger car tires usually falling between 75 and 105 in the load index ratings. In this case, a tire that’s rated with a 97 number can safely carry 1653 pounds at each tire. 
  • Considering that a fully-loaded car, with passengers and luggage, might weigh in at around 5000 pounds, this is a fairly generous margin of safety. 
  • T – This final letter is the tire’s speed rating. Speed ratings range from B (31 mph) to Z (149 mph or over). In this case, a T speed rating means this tire is safe at speeds up to 118 mph. 
There is a bunch of other coded information on a tire, indicating the number of plies, manufacturer’s plant code, brand characteristics, week and year of manufacture and other important points. This starts to get a little esoteric, and changes from one brand or style of tire to another. 
It’s ben our experience at L & M Tire & Wheel that, for the average driver, size designations are the most important thing they need to know, and the thing they ask about most often. 
We hope that this brief rundown on tire sidewall information is helpful to you. If you’re in Hanover, PA and looking for some of the best deals on tires anywhere in the Southern Pennsylvania area, you’ve come to the right place at L & M Tire & Wheel. It’s worth the short drive to Abbottstown, PA for exceptional customer service and low, low prices on premium-brand tires and wheels! Schedule an appointment, today!
  Posted in: Tire 101