Trail Manual · Gear Ratio Calculator
Axle Gear Ratio Calculator
Select your vehicle and trim to load factory specs as defaults. Set your target tire size. The calculator gives you a recommended gear ratio, shows the RPM impact at highway speed, and computes your crawl ratio — before and after.
Vehicle Setup
Current Setup (auto-filled — edit to override)
Axle Ratio
Select a trim above
TC Low Ratio
Transfer case
Trans 1st Gear
Used for crawl ratio
Trans Top Gear
Used for highway RPM
Stock Tire Diameter
Diameter (inches)
Factory size
Target Tire Size
Common metric conversions: 285/70R17 = 33.0" · 315/70R17 = 34.4" · 35x12.5R15 = 35.0"
Results
Select a vehicle, trim, and target tire size to see your recommendation.