## Problem: Big
Tires (click here for a statement of the problem)

# My Solution.

## We can express RATE

as a __ratio__ between DISTANCE travelled and the TIME it takes
to travel that distance.

## In the case of the affect of tire size
on the speedometer reading, we need to consider a __ratio__
between the RATES:

## when

# aaa

## We can also look at this problem as related
to the __ratio__ between the CIRCUMFERENCES of the tires. Recall
that CIRCUMFERENCE can be expressed by the relationship:

##

## where
*r* is the RADIUS and *d* is the DIAMETER

## The ratio between the CIRCUMFERENCE of
the original tires and the replacement tires is:

## So,

# aaa

## So either way, the problem is
reduced to the ratio between the DIAMETERS of the tires:

#
&

#

#
=

#

## Multiplying the ratio by 55mph:

##

## That is to say, when the speedometer
reads 53mph, the actual speed of the truck is 55mph.