Help with wheels diameter

[Hondaracing819]

I bought this speedometer for my moped and it is digital. in order to calculate the speed i need to find out the diameter of the front wheel in mm. So i did it and it came out it 56.5. and it said take the mm and times it by pi(3.14). so first it said

WS = mm x 3.14

Anyone know wtf to do.

i did 56.5 x 3.14 and got 177.5 but the place to put the numbers in it is only like this 00.0 then a little number after that.
Help please

[lghickman21]

there is 25.4 mm in 1 inch if that helps you any

[400exrider707]

Originally posted by Hondaracing819
I bought this speedometer for my moped and it is digital. in order to calculate the speed i need to find out the diameter of the front wheel in mm. So i did it and it came out it 56.5. and it said take the mm and times it by pi(3.14). so first it said

WS = mm x 3.14

Anyone know wtf to do.

i did 56.5 x 3.14 and got 177.5 but the place to put the numbers in it is only like this 00.0 then a little number after that.
Help please

So that 177 is your circumference of the tire overall. It is probably more accurate to use a piece of string to get the overall circumference of the tire. Wrap it around and measure how long the string is. If your unit only has 00.0 and is designed for a moped it might not be able to handle the larger tire size on your quad.

[zeppelin]

where did you get the 56.5 from?

im confused..