Jeep Regearing Guide: Choosing Gears for 35s and 37s
Drivetrain guide • Updated September 13, 2026
You fit larger tires, head onto the highway, and notice the transmission dropping a gear on hills it used to climb easily. On the trail, first gear in low range suddenly feels a little too fast. Those are good reasons to look at Jeep regearing—but the right answer starts with your actual axles and transmission, not a tire-size chart alone.
Changing the ring-and-pinion ratio can restore useful torque multiplication after a tire upgrade. It does not add engine horsepower, strengthen an axle housing or increase the vehicle’s rated towing capacity. Here is how to plan a regear that makes sense for the way your Wrangler or Gladiator is driven.
What bigger tires do to your Jeep’s gearing
An axle ratio describes how many times the pinion turns for one revolution of the ring gear. With 4.88:1 gears, the driveshaft turns approximately 4.88 times for one revolution of the differential carrier. A numerically higher ratio is commonly called a deeper or lower gear.
A taller tire travels farther per revolution. That reduces engine speed at a given road speed and reduces tractive force at the ground for the same axle torque. Heavier tires also require more energy to accelerate. Regearing addresses the leverage change; it cannot make the extra mass disappear.
Equivalent new ratio = current axle ratio × new tire diameter ÷ old tire diameter.
For a Jeep changing from a measured 32-inch tire to a 35-inch tire with 3.73 gears: 3.73 × 35 ÷ 32 = 4.08. That is an approximate factory-equivalent baseline, not a recommendation to order 4.10 gears. Added weight, terrain and the transmission may justify a deeper ratio.
Use consistent measurements or the tire manufacturer’s revolutions-per-mile data. Do not mix an advertised sidewall size for one tire with a loaded measurement for the other. If your transmission now hunts between gears, the clutch needs more slipping to get moving, or low-speed control has deteriorated, the tire and gear combination deserves a closer look.
Choosing between 4.56, 4.88 and 5.13 gears
The best gear ratio for 35-inch or 37-inch tires varies with engine output, transmission ratios, actual tire diameter, loaded vehicle weight and available axle gearsets. A four-speed automatic JK and an eight-speed automatic JL should not receive the same recommendation just because both wear 35s.
On a small screen, swipe the table sideways to compare every column.
| Ratio to compare | Why it enters the conversation | What to check |
|---|---|---|
| 4.56 | A possible compromise for some 35-inch daily-driver builds. | Will the engine hold an appropriate highway gear with your load and terrain? |
| 4.88 | More torque multiplication than 4.56; often considered when comparing 35- or 37-inch setups. | Calculate cruising RPM and verify gearset compatibility with both axles. |
| 5.13 | Deeper reduction for combinations needing additional low-speed control or help with larger tires. | Check highway RPM, engine/transmission combination and the axle builder’s limits. |
These are ratios to evaluate, not a universal fitment chart. A lightly loaded Jeep on flat roads has different demands from the same vehicle carrying armor, camping equipment and passengers over mountain passes. Diesel, turbocharged, hybrid and V8 models also need their own calculations.
Put highway RPM and crawl ratio on paper
For a conventional drivetrain with the torque converter locked, approximate engine RPM is mph × axle ratio × transmission ratio × 336 ÷ tire diameter in inches. At 70 mph, a 0.67 overdrive and a 35-inch tire produce about 2,053 rpm with 4.56 gears, 2,197 rpm with 4.88, and 2,310 rpm with 5.13. These are illustrative calculations, not the specifications of a particular Jeep.
Crawl ratio is first-gear ratio × transfer-case low-range ratio × axle ratio. Deeper axle gears increase that reduction, which can make slow obstacle work easier. Tires still change ground speed, and an automatic’s torque converter adds behavior the simple crawl-ratio calculation does not capture.
Identify both axles before ordering a regear kit
“Dana 44” is a family name, not a complete parts specification. A JK Rubicon Dana 44 gear package is not automatically compatible with a JL/JT axle. Front and rear applications, gear rotation, bearing dimensions, pinion splines and factory locker provisions can differ.
- Confirm model year, platform, trim, engine and transmission.
- Identify the actual front and rear axle assemblies using build information and axle identification markings. Account for previous swaps.
- Verify current ratio, carrier or locker type, carrier-break requirements and the intended new ratio.
- Confirm whether different carriers, thick-cut gears, bearings or other application-specific parts are required.
The front and rear axle ratios must be a compatible matched pair for four-wheel-drive operation. Do not engage 4WD with an unmatched regear. Also use appropriately matched tire rolling circumferences front and rear.
Plan the parts, installation and total cost together
Start with complete gear packages if you need both axles. Compare the contents with separate ring-and-pinion sets and differential installation kits. A package title alone does not tell you whether fluids, carriers, axle seals or locker components are included.
For the same JK Rubicon application, OTC also lists the Revolution Gear 5.13 package with Timken bearings. Compare the ratio after confirming the drivetrain details; a different ratio is a different driving decision, not simply an upgrade tier.
A useful installation quote should itemize both axle gearsets, bearings and setup parts, labor, fluids, calibration and any required carrier or locker change. Ask what happens if the teardown reveals damaged bearings, worn shafts or a compromised housing. A single advertised labor price rarely tells the whole story.
Gear setup requires accurate pinion depth, backlash, bearing preload and tooth-contact pattern. These measurements determine gear life and noise. If a locker is also planned, discuss it now: changing a full differential carrier during the regear can avoid repeating much of the setup labor. Our Jeep lockers comparison explains the choices.
Leave time for break-in and recalibration
Book the gear job far enough ahead of a trip to complete the manufacturer’s break-in. For example, Revolution Gear’s break-in instructions call for short initial drives with cool-down periods, restrained driving and an oil change after 500 miles. They also restrict towing and off-roading during that initial period. Follow the complete current instructions for your exact gears and lubricant, including any separate front-axle guidance.
Update tire-size and axle-ratio settings where supported and required for your Jeep. Verify speedometer accuracy, transmission behavior and the absence of drivetrain faults afterward. Calibration is not a substitute for correct mechanical installation.
Frequently asked questions
- Do I need to regear my Jeep for 35-inch tires?
- Are 4.88 or 5.13 gears better for 37-inch tires?
- Do both axles need to be regeared?
- Will regearing improve fuel economy?
Do I need to regear my Jeep for 35-inch tires?
Not automatically. Start with the factory ratio, transmission, actual tire diameter and how it drives under its normal load. Frequent downshifts, poor launch feel or inadequate low-range control can justify a regear. Use the calculation above to establish a baseline, then choose with an axle specialist.
Are 4.88 or 5.13 gears better for 37-inch tires?
Neither is universally better. The 5.13 ratio provides about 5% more reduction than 4.88, with roughly 5% higher engine RPM in the same transmission gear at the same road speed. The right choice depends on the engine, transmission, weight, use and supported axle applications.
Do both axles need to be regeared?
For a four-wheel-drive Jeep changing to a new axle ratio, plan a compatible front-and-rear match. Regearing only one axle and using 4WD can damage the drivetrain.
Will regearing improve fuel economy?
It may reduce inefficient gear hunting in some combinations, but better mileage is not guaranteed. Tire mass, tread, rolling resistance, aerodynamics, speed and the selected ratio all affect consumption. Choose for appropriate operation, not a promised MPG gain.