Drivetrain

Drivetrain calculators help enthusiasts and builders understand how gear ratios affect acceleration, top speed, RPM at cruise, and towing capability. The final drive ratio - the product of transmission gear ratio multiplied by axle ratio - determines how many engine revolutions occur per wheel revolution.

A numerically higher axle ratio (e.g., 4.10 vs 3.31) provides more torque multiplication at the wheels, improving acceleration and towing capacity but increasing RPM at highway speeds. For a pickup truck towing heavy loads, a 4.10 axle ratio might be optimal. For highway fuel economy, a 3.23 or 3.55 ratio keeps RPM lower at cruise.

RPM at a given speed depends on tire circumference (which determines wheel RPM) and final drive ratio. Understanding this relationship helps you select the right gear ratio combination when swapping axles, changing tire sizes, or building a custom transmission.