kinda a math question

[the_wildthing]

Hmmm...If we assume 100Km/h is the "true" speed, and not just what the speedometer shows, which is sometimes inaccurate, and we assume also that the 195/55/15 is inflated to make the radius of the tire precisely the ff:

195mm x 0.55 = 107.25mm
Diameter of rim: 15in x 25.4mm = 381mm
Diameter of wheel: 381mm + (107.25mm x 2)= 595.5mm
Circumference of wheel: 595.5mm x 3.1416 = 1870.82mm approx.

Now, 100km/h means the car is travelling 100,000,000mm per hour.

So the car is travelling 100,000,000mm / 60 = 1,666,666.67mm per minute.

1,666,666.67mm / 1870.82mm = 890.87 revolutions per minute, assuming a relatively smooth surface and a straight line. We all know that when turning, outer wheels travel farther than the inner wheels, hence more turns. Also, going over bumps or potholes may affect wheel spin.

Of course, I am not a math wizard so the above computation could be wrong.