The last letter in a standard tire size indicates the number of layers used in the construction of the tire. If there is no letter, the tire has the standard 4 plies. A “C” indicates 6 plies, a “D” indicates 8 plies, and an “E” indicates 10 plies. The higher the number of plies in a tire, the stronger the tire is and the more air If there isn't a letter preceding the three-digit numeric portion of a tire size, it signifies the tire is a "Metric" size (also called "Euro-metric" because these sizes originated in Europe). HL = When a tire size begins with an “HL,” it will also end with an “XL.”. This signifies the tire has higher load carrying capacity than an 255 (Tire Width): The tire width is 255 millimeters from sidewall to sidewall (just over ten inches). 45 (Aspect Ratio): The tire’s sidewall is 45% of the tire’s width, which means the sidewall is about 114 millimeters or just over 4 inches. R (Construction Type): Radial tire, the most common type of tire produced today. The dimensions computed by our calculator use the following equations: Section Height = Aspect Ratio × Tire Width. Tire Diameter = Wheel Diameter + 2 × Section Height. The aspect ratio and tire width are measurements acquired from the tire code. The tire width is the 3-digit number preceding the forward slash ( / ) in the tire code in units Step 1: Learn the three main tire size numbers. The first thing to look for when looking to buy new tires is the current tire size that’s on your vehicle. I’ve outlined in-depth above what each tire size number means and left a quick overview below: Passenger vehicles/Truck tire size numbers (225/75R17) The first number = tire width 55 refers to the profile of the tyre, or the distance between the wheel and the edge of the tyre, looking at it from the side. The number is the percentage of the width of the tyre. It is commonly known as the “aspect ratio”. So, the profile of our example tyre is 55% of 205mm, or 112.75mm. This number also increases in increments of 5. To make it easier for you to pick the right tires, we’ve made a chart that shows all the different tire sizes, how wide the rims should be, and how much weight each tire size can handle. With this helpful chart, you’ll have all the information you need to pick the best tires for your trailer. 8 – 9 – 10 – 12 – Inch Trailer Tire Size The first number in the sequence is the tyre’s width measured in millimetres, so in this example we can tell that the tyre is 195mm wide - a common width for superminis and smaller family cars. The next number shown is the tyre’s height, but this is expressed as a ratio rather than a measurement. So in our example the height is 65% of the .

how to read tyre dimensions