Hey, im making an AVR speedometer, and i need to see if my math is right.

I have an 8 inch tire. i am going to set a tiny eye up to measure approximately 4 ticks per 1 revolution of the tire.

lets see if i got this right: the circumference of the tire from 8 inch diameter is 25.12inches. meaning the tire would move 25.12 inches in 1 revolution.

in those 25.12 inches, the CPU will measure 4 ticks.

if i divide 25.12 / 4 ticks in one rev. i get 6.28 inches per tick.

here is how i am going to do it:

take the number of ticks the processor gets from the sensor for 1 second. then multiply this by 6.28 (distance per tick).

then i multiply it by 60, to give inches per minute, then multiply again by 60 to give inches per hour.

then take that divide by 12, to get feet per hour. and then take that and divide by 5,280 feet to get miles per hour.

Do i have my math right? or no. it just doesnt seem right. for example if i am going 25 miles per hour, thats 70 ticks per second. that seems kinda fast..