What are the actual outside tire diameters for sizes - 225/55/16 and 245/40/18?

Thanks alot. I did search but came up with alot of nothing.

 

Chuck,

Try this :

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

 

chuckie my friend

here you go:

save this link you will thank me tremendously for it

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



edit: holy **** how did cxp beat me to it

 

thanks fellas nice link

according to that they are almost exactly the same diameter. the 18 is actually .7 mm smaller

 

if u want comfort go 245/45/18

 

I was checking that out but it's a whole inch taller. then we get into the acceleration factor

 

how does rim width factor in when figuring diameter? I noticed there's nowhere to puch that into the equation.

 

it's not in the equation coz.... it's NOT part of the equation?

let's get some notation, say it's W/R/D (width, ratio, and diameter)

to get the overall diamter of the tire?

((W x R/100 x 2) / 25.44) + D

so 245/45/18, the diamter is 245 x 0.45 x 2 / 25.4 + 18

the 25.4 in equation, that's inch to mm conversion. 1inch = 25.4mm

 

I just figured the width of the rim might stretch the tire more or less

 

oic. yes technically it has some effect, but it's like couple mm so it's kinda insignificant

 

There is also the rub factor with the 245/45/18. Same issues with 20s and 29s fat.

 

Nice link guy's