You may have looked at your tires occasionally and noticed that beyond just tread, there are also numbers on your tires. They may look something like 285/50R 20 89V and seem like they might be secret technical markings. These are not secret markings , even if you may not understand them right now, this article will help you understand what it is that the manufacturer is saying with the numbers and help you next time you go to buy new car tires . Take the example above, 285/50R 20 89V and break it apart. Each of these parts have a specific meaning. First number 285 This is the distance in millimeters from the sidewall edge to the sidewall edge or else considered the width. The larger this number is, the wider the tire will be. Second Number 50 This is the tire's aspect ratio. It tells how tall the tires are in comparison to how wide they are. This can tell you what the tire is used for. If it is a lower number like 50 it is better for steering and maneuvering. Letter "R" There are two things that could go here. Usually it will be an R which means that it is a radial tire. If there is a B it is for Bias, which is a older way of making tires and is not used very often anymore. Third Number 20 This is the rim diameter in inches. Pay particular attention to this number because it needs to match the size of your rims. If you change rims, you may need to buy new tires that will fit your rims. Fourth Number 89 This number indicated the amount of weight allowed on each tire. This is a little more cryptic because 89 has no real world significance. An tire with an 89 can actually carry 1,260 pounds of pressure, and that is just on that one tire. If you want to know how much the whole car and passengers can weigh you will have to multiply by four as long as all of your tires are the same as they should be. Letter "V" This is the speed that the tires can run at for an extended period of time. Meaning that while you may be able to go above the max speed for a few seconds, it is not recommended to do so for a few minutes. V is a fairly common number and it means no more than 149 mph. Other letters you may see here include S which means 112, T which means 118, U which means 124, and sometimes you may see W which is 168, or Y which is 186. If you see a ZR it strictly means that the speed is over 149, but does not say anything for what the exact speed is.