1994 Honda Civic Owner's Manual - Page 186

Tire Information Tire Size Designation A tire's sidewall is marked with a tire size designation. You will need this information when selecting replacement tires for your car. The following explains what the letters and numbers in the tire size designation mean. (Example tire size designation) P175/65R1481H P - Applicable vehicle type (tires marked with the prefix "P" are intended for use on passenger cars; however, not all tires have this marking). 175 - Tire width in millimeters. 65 - Aspect ratio. The tire's section height as a percentage of its width. R -Tire construction code (Radial). 14 - Rim diameter in inches. 81 - Load Index, a numerical code associated with the maximum load the tire can carry. H - Speed Rating Symbol. See the speed rating chart in this section for additional information. J - Rim contour designation. Tire Speed Ratings The chart below shows many of the different speed ratings currently being used for passenger car tires. The speed rating symbol is part of the tire size designation on the sidewall of the tire. This symbol corresponds to that tire's designed maximum safe operating speed. Wheel Size Designation Wheels are also marked with important information that you need if you ever have to replace one. The following explains what the letters and numbers in the wheel size designation mean. (Example wheel size designation) 14 x 5J 14 - Rim diameter in inches. 5 - Rim width in inches. Technical Information