The RPM (Revolutions Per Minute) calculation for a vehicle involves determining the rotational speed of the engine and the wheels based on the tire diameter, vehicle speed, and transmission ratio.
Transmission Ratio:
\[ \text{Transmission Ratio} = \frac{\text{RPM} \times \text{Tire Diameter}}{336 \times \text{Vehicle Speed}} \]
Wheel RPM:
\[ \text{Wheel RPM} = \frac{\text{Vehicle Speed} \times 336}{\text{Tire Diameter}} \]
Suppose you are driving at 60 mph with a tire diameter of 23 inches and the engine RPM is 3500. Using the formulas:
Transmission Ratio:
\[ \text{Transmission Ratio} = \frac{3500 \times 23}{336 \times 60} \approx 3.99 \]
Wheel RPM:
\[ \text{Wheel RPM} = \frac{60 \times 336}{23} \approx 877 \text{ RPM} \]