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First of all, it is necessary to know that this depends on the diameter of the tire used in your vehicle. With that in mind, we'll do a calculation to set the number of revolutions per minute (RPM) you'll get using a certain ratio on various tire measurements. Step 1: Calculate the Reason for the Crown and Pinion Calculating the relationship between the crown and the pinion is very simple, for this, just count the number of teeth of the crown and the pinion, and divide by the other, you will have the value of the ratio of your crown and pinion. Example: crown with 44 teeth / pinion with 9 teeth = 44: 9 = 4.88 Step Two: The Tire Diameter To reach the RPM number, we will use the tire diameter in inches. Some tires already come with the size of the inch identified on the side, for example 31 × 12.5 R15, where 31 would be the inch diameter of the tire. This is usually quite common in trucks and buses. Now that you know the diameter of your tire, we will calculate the revolutions per minute. To make this calculation, we take into account the vehicles under the following conditions: Speed: 65mph (about 100km / h) Manual Transmission Vehicle with Final Ratio 1: 1 The formula applied is as follows: RPM = MPH (65) x Trans Ratio x Rearend Ratio x 336 ** Tire Diameter With this in mind, we can see that the larger the tire, the higher the speed for the same RPM. We also noticed that the lower the crown / pinion ratio, the higher the speed. For more strength will be the opposite: smaller tire diameter and higher crown / pinion ratio. It is a real relationship. NOTE: Vehicle speed (mph), engine speed (rpm), tire diameter (inches), trans gear ratio, and rear axle gear ratio are all interrelated. If you know four out of five of these values, you can determine what the unknown value is (or what it needs to be to achieve your desired goals) ** The unreduced formula for finding vehicle mph involves multiplying engine rpm by the number of minutes in an hour (60) and multiplying the tire diameter by pi (π) to find the circumference of the tire in inches. Then multiply both of these individual products together, and divide by the overall gear ratio times the number of inches in a mile (63,360). “336” is simply the reduced, rounded-off whole-number value of these various constant values. I, particularly, prefer higher speed.