Performance Tools
Regear Calculator for Lifted Trucks
Calculate the correct gear ratio after installing bigger tires. Determine which ring and pinion gears you need to restore factory power, fuel economy, and speedometer accuracy.
Enter Your Setup
Check your axle tag, door sticker, or window sticker.
Recommended Ratio (Factory Match)
Start here. Installing 4.30 gears will restore your truck to stock-like performance and MPG.
Current "Feel"
3.30
feels sluggish
Performance / Towing
4.56
more torque
⚠️ Power Loss Alert
Your bigger tires effectively reduced torque by 12.9%. Without regearing, your transmission may hunt for gears and overheat on hills.
Why Regear After Bigger Tires?
1. Restore Lost Power
Larger tires increase the leverage against your axle, making your truck feel weak and sluggish. Regearing increases mechanical advantage, making the engine's job easier and bringing back that "snappy" acceleration.
2. Save Your Transmission
When tires are too big for your gears, the transmission constantly unlocks the torque converter and downshifts to maintain speed. This creates excess heat—the #1 killer of automatic transmissions.
3. Fix MPG & Speedometer
While a speedometer programmer fixes the gauge, only mechanical regearing puts the engine back in its efficient RPM powerband, often recovering 1-3 MPG lost to the lift kit.
Common Gear Ratio Upgrades
| Vehicle Type | 33" Tires | 35" Tires | 37"+ Tires |
|---|---|---|---|
| Jeep Wrangler (JK/JL) | 4.10 or 4.56 | 4.56 or 4.88 | 5.13 or 5.38 |
| Toyota Tacoma/4Runner | 4.10 ~ 4.30 | 4.56 or 4.88 | 5.29 |
| Ford F-150 / GM 1500 | 3.73 or 4.10 | 4.10 or 4.56 | 4.56 or 4.88 |
| Diesel Trucks (HD) | Stock (3.42) | 3.73 or 4.10 | 4.30 or 4.56 |
*General guide only. Always consider your specific engine (V6 vs V8 vs Diesel) and transmission ratios.
Frequently Asked Questions
Do I need to regear both axles?+
YES! If you have a 4x4 or AWD vehicle, you MUST regear both the front and rear axles to the exact same ratio. If they don't match, engaging 4WD will bind the drivetrain and cause catastrophic failure of the transfer case or axles instantly.
Can I just use a programmer instead?+
A programmer corrects the speedometer and shift points on automatic transmissions, which helps a lot. However, it cannot physically change the mechanical leverage. For small tire increases (e.g. 31" to 33"), a programmer is often enough. For big jumps (31" to 35"+), mechanical regearing is necessary to save the transmission.
How much does regearing cost?+
Expect to pay significantly. A quality regear job typically costs $1,500 to $3,000 per vehicle (for both axles). Parts (ring & pinion, install kits, fluid) run $800-$1,200, and labor is intensive (6-10 hours). It is one of the most expensive but valuable mods for lifted trucks.
What is the "Break-In" procedure?+
New gears require careful break-in to work harden the metal surfaces. Generally: Drive 15-20 miles gently, stop and let axle cool completely. Repeat. No towing or highway speeds for the first 500 miles. Change differential fluid at 500 miles to remove metal break-in particles.