chuckb

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.

cxp2001

iTrader: (1)

Chuck,

Try this :

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

NT2SHBBY

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

chuckb

thanks fellas nice link

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

NT2SHBBY

if u want comfort go 245/45/18

chuckb

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

chuckb

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

rominl

iTrader: (4)

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

chuckb

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

rominl

iTrader: (4)

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

Neo

iTrader: (3)

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

LEXUS_KID

iTrader: (4)

Nice link guy's