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Physics made easy



I was bored here at work and decided to put the degree I just earned to the
test.

>225/50-16 diameter is 24.88
>225/60-15 diameter is 25.6
>
>I'd have to go back and dig up a physics text to calculate the difference
>in revs per mile. 

There really is no physics involved in the calcutation, just some High
School Algebra.  First, take the height of the tire (diameter) and multiply
it by pi (3.14).  This will give you the circumference of the tire. 

For 24.88 inches tire, the circumference is 78.123 inches.

Take the inverse of the circumference (1/circumference) and this will give
you how many revs are in 1 inch (very small number)

For the 24.88 inches tire, the revs per inch is .0128002 rev/inch.

We all know that there are 12 inches in a foot and 5280 feet in a mile
(which is 63360 inches in a mile) so take this big number and multiply by
the previous calculation, which will give you revs per mile.

For 24.88 inches tire, the revs per mile is 811.02.

For the 25.6 inches tire, the revs per mile is 788.21.

Of course we could all have looked up the manufacturers spec for revs/mile
on each tire, but this was more fun.  

I hope I did not insult anyone with this message.




Chris Roth @ work....shhhh don't tell my boss 
caroth@holly.colostate.edu
85 SVO (Bright Red)
86 SVO (Silver Metallic)