mm or cm

[jockboy]

i believe it's mm just to be sure i know that tyres 275/75/16 is 32.24 and 285/75/16 is 32.83, but is .83 and .24 is it in mm. 1.83% difference in height if it is mm

beetween 275 and 285 if in mm does that make it 2 and a half inches of a difference. ?

had 265/75/16 before want 275's now if in inch diferrence i think.

thanks for patience and help

 

[180degrees]

getting yourself confused mate one is in inches measuring the overall diameter the other uses the base width and multiplies it by a ratio to find the the height of the tyre wall.

to quote myself from another thread

most people are to lazy to do the 5 second conversion with microsoft calculator

ie: 33x12.5r15 =

    33*125.4 = 838mm
    12.5*25.4 = 317.5mm
    r15 = r15 no surprises there


its a tad harder converting back to inches from a 265/75r16 but this is all you do.

ie: 265/75r16 (265 is the tyre width and 75 is the aspect ratio of width to wall height its 1:0.75 in this case r16 is just the wheel diameter in inches..again no surprises there)

    265*.75 = 198.75mm (this is your tyre wall height)
    r16*25.4 = 406.4mm
    sum of the sections
    =198.75*2 (upper and lower walls of the tyre) + 406.4 = 804mm
    804mm/25.4 = 31.7"
    265mm/25.4 = 10.4"


obviously these figures change per per tyre manufacturer but the method of converting to and from remains the same.

cheers

if you still need help making sense of those equations just say so, I do some pretty hard maths at uni for my engineering subjects so stuff like that ^ comes pretty easily to me.

 

[equipt]

Stuff that. Just use this.

http://www.miata.net/garage/tirecalc.html

 

[180degrees]

that only gives you a general idea of the size for that category, my method allows you to calculate it for both that and the individual tyre

 

[Busiboy]

http://www.exploroz.com/Vehicle/Tyres/SizeCalc.aspx

 

[jockboy]

thanks guy's