Tire Size Guide: How to Read Tire Numbers and Letters Tire Class. The tire class is indicated at the beginning of the tire code. Typically, you'll see the letters P, LT, or Tire Width. The three-digit number following the tire class is the tire width. The width is the distance of the tire What Do The Numbers On Tires Mean? Tire service type ratings. Most tire sizes begin with one or more letters -- for example, P or LT. The letter tells us P = P-Metric (Example: P215/65R17 98T). P-Metric tires are the most common type of tire. The P stands for passenger Metric / Euro-Metric The number 185 is the tire's width in millimeters, from one sidewall to the other. The number 60 after the forward slash character means the tire's height from rim to tread is 60 percent of its width, which again is 185 millimeters. R14 means the tire is meant to fit on a 14-in. diameter wheel. The set of numbers straight after the tyre width refers to the thickness of the tyre wall (or aspect ratio), which is a percentage of the width. So, in this case, 55 would have a height equal to 55% of the tyre's width. This number is often referred to as the tyre profile. Tyre construction P denotes passenger-car tire. Some may start with an LT prefix, used on heavy-duty trucks. The number 235 is the cross-section width in millimeters, and 65 is the ratio of sidewall height to .

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