A typical tire size might read: P 205/65 R 15 92 H Here's what that means. P — This denotes a Passenger or P-metric tire built to U.S. standards. Here are other possible prefixes: LT is for a light truck. ST is for a special trailer. T is for temporary, usually indicating a spare tire. European-standard tires won't have a prefix letter at all.
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 toIt is indicated by a letter of the alphabet, which refers to a table that is common to all manufacturers. Each letter corresponds to a certain maximum speed. It starts from letter "A", the only one which is broken down with numbers (A1, A2, A3, etc.) and which allows speeds of between 5 to 40 km/h.Is the width of the tire measured in millimeters from sidewall to sidewall. The first three-digit number in the tire size refers to the tire width. For instance, in a size P215/65 R15 tire, the width is 215 millimeters. Aspect Ratio Is the ratio of the height of the tire's cross-section to its width. 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
The most basic information that you'll find on a tire's sidewall is related to its size. This is normally written as 185/65R15, for example, though you'll sometimes see "P" (for passenger cars)
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