1. Changing Tires

2. Warm up: Free write  In 20+ words,  How do you think changing the tire size on a vehicle will affect mileage or speed?

3. Finding the Circumference of a Tire

4. LT 265/75R16 Example

5.  Step 3  198.75mm/25.4mm = 7.82 inches  Step 4  D=2H+R  D=2(7.82)+16  D=31.64 inches

6.  Step 5  C=D  C=3.14 (31.64)  C=99.3496

7. Effect of changing factory – installed Tires  The following principles apply when determining actual distance and speed traveled according to tire size:  Actual mileage = k odometer reading (mileage)  Actual speed = k speedometer reading (miles per hour)  where k =  circumference of bigger tire  circumference of factory-installed tire  Since the value of k = 1.1128 for the two tires in comparison, 1.1128(20,000) = 22,256  miles (actual) and 1.1128(60) = 66.768 miles per hour (actual).