Quote:
Originally Posted by slowhiteboy  if you read my thread that is what I said. The point is that there are several tire calculator sites besides Tirerack thay say 747 so again what I am looking for is the definitive answer to the question, 747 or 770? |
Man, this is ridiculous.
When you get the tires, use a tape measure and go around the tire to get outer circumference, in inches. Divide by 12. Or you can go Pi*diameter/12. Diameter is easiest and most accurate, because you can do it with the car on the tires, which decreases their circumference slightly, by flattening the bottom portion of the tire. Put a ruler on top of the tire and measure from the ground to the bottom edge of the ruler. 3.141592653589793 times diameter, divided by 12, gives you feet per revolution.
When you get that number (it'll be about 7.3304, for a 28 inch tall drag tire), you can divide 5280 feet/mile by your 7.3304 feet per revolution...
Feet cancel, leaving you with, in this instance, 720 revolutions per mile.
Pirelli PZero Neros are 742 per mile. Use 740 for your tuner. Check it against a mile marker and see if it's close.
Hoowee, that's a lotta math for a Saturday morning.
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