And, often tyre diameters are referred to in inches…so we convert to inches – 625mm / 25.4 = 24.6 so we’d call that a 25 inch tyre. To find the overall diameter of the tyre it’s two sidewalls of 97mm each, and the 431mm rim so: ( 97mm x 2 = 194mm) + 431mm = 625mm. Specs are based on a properly inflated tire mounted on the measured rim size and. Tire specifications may vary slightly from the calculations. And that’s in inches! There’s 25.4mm to an inch, so to convert 17inches to mm = 17 x 25.4 = 431mm. Aspect Ratio : Rim Diameter: Sidewall Height: Circumference: Revolutions: Our tire size conversion calculator will help you convert metric tire size to inches to better understand your tires dimensions. Confusing, but that’s the way it is.įinally, the 17 is the rim diameter. This means that the tryre is a bit higher. The only problem is that they only come in 225/45/18 here in AU. The calculator will make a list of optional tyre sizes for the new wheel. I came up with Michelin Primacy 3 STs (reviews are really good). Tyre Size Calculator helps you determine tyre size when you place larger wheels. My current tyres arent the quieteset and I have been looking online to see what tyres have the least noise. Use Tyroolas Tyre Size Calculator to compare your existing tyres and those you are eyeing in terms of overall diameter, sidewall height, tread width. Our tyre size comparison calculator takes the measurements of two tyres and compares the overall diameter, tread width, sidewall, and difference percentage (). So to find the sidewall height we multiply 215 * 45% = 97mm. I have a VRS wiith 225/40/18 tyres (40 being the aspect ratio). A very useful tyre calculator when searching for tyres that are a different size than stock. It refers to the aspect ratio, or sidewall height. The first number, 215, is the tread width in millimetres. So what do those numbers mean? Let’s take a look at that 215/45R17 tyre: The “R” stand for Radial, a type of tyre construction, again not relevant to sizing. The 87W is the load and speed rating, and that’s important but not relevant to sizing. The number 70 is the aspect ratio, sometimes. The numbers you’re looking at for size in the picture above are 215/45/R17. The number 225 is the width of the tire in millimeters, measured from the inner sidewall to the outer sidewall. The Tyre Size Calculator helps you compare your existing vs new tyres by giving you some comparison measurements and advice.Ī tyre’s size is found on the sidewall of the tyre, and it looks like this: Very often people wish to change their tyre’s dimensions 4X4 owners often want taller tyres for better offroad performance, and sports car owners often want wider tyres for looks and corner grip, or bigger brakes are being fitted.there’s many, many reasons to change your tyre size, but first you need to understand how sizing works. The easiest way to buy new tyres is just to drop your car at a shop and tell them “new tyres, please”.īut that’s not necessarily going to get you the best tyre for your needs, whether you’re a 4X4 tourer, tower or racetrack lover. Need help understanding sizing like 215/35/17 or 33×10.5×16? Read this…

Tyre aspect ratio calculator