Question 1

What is the difference between transmission and final drive ratio?

Accepted Answer

Transmission ratio changes with each gear shift. Final drive ratio (differential) is constant and multiplies all transmission ratios. Overall ratio is transmission ratio times final drive ratio.

Question 2

Should I get shorter or taller gears?

Accepted Answer

Shorter gears (higher number like 4.10) improve acceleration and towing but increase highway RPM. Taller gears (lower number like 3.23) improve fuel economy and reduce engine wear but slow acceleration.

Question 3

How do tire size changes affect gearing?

Accepted Answer

Larger tires effectively create taller gearing (slower acceleration, lower RPM at speed). A 10% larger tire is like changing from 3.73 to 3.39 gears. Smaller tires do the opposite.

Question 4

What RPM should I cruise at on the highway?

Accepted Answer

Most modern engines are efficient between 1,500-2,500 RPM. Higher RPM increases fuel consumption and wear. Calculate your cruise RPM when selecting final drive ratio.

Gear Ratio Calculator - Transmission Speed Tool