Any way to calculating the tire sidewall height?

[gpktm]

Is there any way to calculate the height of a tire sidewall? (According to sidewall markings)

[NightEye]

Wasn't it something with the bold number?
215/45 R18
Not really sure though... Or actually, not at all... :roll:

[Bjolletts]

If a tire is 245 / 45 for example it means that its 245mm wide, and the sidewall is 45 % of the width. (not 45 mm ! )

[sky^sp]

are you sure about that? i wouldn't bet the farm on it.. just went outside and measured two wheels 215/45 and 195/50 - guess what the sidewall said? yup, 45 mm and 50 mm.
given your calculation this would make the sidewalls 96 mm and 97,5 mm high, which they aren't. btw this sidewall doesn't refer to the toal height, which is about 20 mm more than the actual sidewall height, it just refers to the straight vertical part of the side of a tire. the rest is considered the errr tread (?)

[rvieira]

Hi Guys,

Bjolletts is right! If you take a 250/45 tyre, it has 250 wide and 112.5 sidewall, thats mean, 112.5 = 250 x 0.45. All mesures in mm!!

Sky^sp is right too. The 45% excludes the the band (sorry I'm not sure about this term in english!!!) tyre, that is about 25 mm high!

[Bjolletts]

Before posting I double checked on the Bridgestone,Michelin and Pirelli websites just to be sure and they all say that the later number is the aspect ratio between the tread width and sidewall height so in my mind there can be no argument about that.

However ... exactly what they define as the "sidewall" and "tread width" is an other matter which I dont know :roll:

[nb]

It's the ratio of sidewal height / tread width in percents, don't doubt that. But how it is measured I'm not sure. When modelling I have always used the exact values. At least this gives a sort of systematic error.