We distinguish three different systems of tire description: Inch system (It is well known from tire size readings like 5.00 - 16 or 4.50/S/18), the Alphanumeric System (the descriptions on tires are like MT 90-16) and the Metric System (for example 130/90 - 16). The last numbers are easy to read, they describe the rim size. Before that number there is generally a dash or one of the letters S, H or V. This is key to speed range: (H) tires are admissible for speeds up to 130 mph, (S) tires are up to 112 mph, and (V) tires for 150 mph and up. Alphanumeric System and Series 80 are describing low-profile tires, which means the height is small than the width and the proportions to the width is fixed. Only in the Standard Inch-System can we find tires with equal width and height which is then a square-profile.