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The dash - indicates the tire construction is bias-ply but this could be an R if the tire is radial. Some manufacturers build off-road tires using inches instead of millimeters so you may see sizes like 3317 This simply means the total height of the tire is 33 inches and it fits a 17-inch wheel.
145 145 165 165 195.
What do numbers on tire size mean. Is the ratio of the height of the tires cross-section to its width. The two-digit number after the slash mark in a tire size is the aspect ratio. For example in a size P21565 R15 tire the 65 means that the height is equal to 65 of the tires width.
The bigger the aspect ratio the bigger the tires sidewall will be. Tire size specifications are outlined by the numbers and letters found on the sidewall of tires. It is important that we understand tire geometry and be informed of the parameters that govern their performance.
Tire sizes are defined by specifications such as the type width aspect ratio speed rating tire construction type and service description. The two-digit number that usually follows the tires section width tells us the aspect ratio or tire profile measurement. In this example the 45 indicates that the sidewall distance from the wheel rim to the outside of the tread is 45 of the section width.
The first letter on a tire indicates the tires class. P designates this tire as a passenger car tire an LT before the tire size would mean the tire is a light truck tire and a European metric tire would have no letter before the tire size. 245 Section WidthTread mm.
Next you will find a slash and then another set of numbers. The aspect ratio sometimes called the tires profile. This number is a percentage that indicates the tires height vs.
In the example above the aspect ratio of our tire is 65 meaning that this tires height is 65 of its width. If theres no letter before the first number you have a metric tire most commonly referred to as European size. Its also measured in millimeters but may have different load capacity than a P or LT tire.
TIRE WIDTH The three-digit number following the letter is the tires width from side to side looking at the tire head on in millimeters. Also called the section width this measurement is taken from outer sidewall to inner sidewall. The final number group the 18 is the size of wheel the tire fits.
In our example size the tire will fit a 18-inch wheel. Some manufacturers build off-road tires using inches instead of millimeters so you may see sizes like 3317 This simply means the total height of the tire is 33 inches and it fits a 17-inch wheel. The tire numbers include.
145 145 165 165 195. Such tires are for specific use and not to be mixed with regular tires. Additionally some tires use rim diameters in millimeters but these are rare.
Michelin PAX run-flat tires which are limited Original Equipment OE tires in the US use this system. Understanding Three Numbers in Tire Sizes The first number in a tires size say 225 is the width of the tire in millimeters. This is pretty straight forward except that in the days of buying tires sized by the inch remember 311050x15 the first number was the height rather than the width.
Back then it was inches not millimeters. The first number is your overall diameter of the tire. In this example the tire diameter or height is 33 inches tall.
The second number represents the width of the tire. In most cases with inch measurement tires the width will have a50 decimal after the initial number. As an example if a tire size has two sets of numbers 6-12 500-15 112-24 then the first number 500 -15 is the approximate width in inches and the second number 500- 15 is the rim diameter in inches.
The P stands for PMetric. If your tire size starts with LT rather than a P then it identifies the tire as a Light Truck tire. 225 identifies the tire section width which is the measurement of the tire from sidewall to sidewall in millimeters.
This measurement varies depending on the rim to which it is fitted. An example of tractor tire sizes expressed in the standard format would be 149-42. The 149 means the tire is 149 inches wide and the 42 tells us that this tire fits a 42-inch diameter wheel.
The dash - indicates the tire construction is bias-ply but this could be an R if the tire is radial. The load index and speed rating or service description are the numbers that follow the tire size. The load index tells you how much weight the tire can support when properly inflated.
Load indices range from 75 - 105 for passenger tires with each numeric value corresponding to a certain carrying capacity. After the tirewheel size there is often a gap followed by a set of numbers and letters. These denote the tires load index or how much weight the tire can carry.
The letters and numbers. The ETRTO size specification 37-622 indicates the width of 37 mm and the tire inner diameter of 622 mm. This dimension is clear and allows for precise classification of the rim size.
28 x 140 states the approximate outer diameter 28 inches and the tire width 140 inches. For example a load index of 81 means that the tire can carry up to 1019 pounds. Load index ratings for the average vehicle range from 75-100 but some tires can range all the way up to 150 which equates to 7385 pounds.
The next two numbers after the width of the tire show the sidewall height in the percentage of the tires width. So if the tire markings indicate P22545R17 91V it means that the height of the sidewall is 225 multiplied by 055 or 10125 millimeters. The number 45 means that the height is equal to 45 percent of the width.