Off-Road Gear Ratios Explained: How to Pick the Right One

Last updated on October 22nd, 2026 at 06:10 pm

A gear ratio tells you how many times the driveshaft turns for each turn of the wheels. A 4.10 axle ratio means the pinion spins 4.10 times per wheel revolution.

A numerically higher ratio such as 4.56, 4.88 or 5.13 sends more torque to the tires, so big tires climb and crawl better, but the engine turns faster at highway speed.

Numerically lower ratios such as 3.21 or 3.55 favor cruising and fuel economy. You find the ratio by dividing the ring gear teeth by the pinion gear teeth, and you restore it after a tire change by scaling it with the tire height.

Changing tire size? Use the free regear calculator for the target ratio and highway rpm, or read on for the math behind it and the crawl-ratio and tooth-count checks that other guides skip.

How to read an axle gear ratio

The ratio is ring gear teeth divided by pinion gear teeth. A ring gear with 41 teeth and a pinion with 10 gives 4.10:1. West Coast Differentials, a gear supplier, defines it the same way: a 3.73:1 ratio means the driveshaft turns 3.73 times for every turn of the wheel.

Most axles carry the ratio on a tag or stamp on the differential cover or in the build sheet. If you can't find it, counting the teeth on the ring and pinion gives the answer.

What a hunting tooth is, and why it matters

A gear pair is called a hunting tooth set when the ring and pinion tooth counts share no common factor. Gear specialist Hermann Stadtfeld, writing in Gear Technology, describes it this way: each pinion tooth eventually meshes with every slot on the ring gear.

In his examples, a 10-tooth pinion on a 30-tooth gear repeats the same three slot groups every revolution. An 11-tooth pinion on a 30-tooth gear hunts through all of them. 41 ÷ 10 = 4.10 is a hunting pair, since 41 and 10 share no factor.

The tool below tells you whether your own tooth counts hunt. It also works out crawl ratio and cruise rpm, using the formulas explained in the sections after it.

Why "higher" and "lower" gears confuse everyone

Shops and writers use the words two ways. Some mean the number (5.13 is higher than 3.73). Others mean the gear (a 5.13 is a "lower" gear because it multiplies torque more, like first gear). That is why two guides can say opposite things about the same axle.

Gear talk gets muddy fast, so it helps to settle the vocabulary before the numbers.

You read or hear	It means	Example
Numerically higher ratio	Bigger number, more reduction, more torque at the wheels, higher rpm at speed	4.88 vs 3.73
"Lower" gear or "lower" ratio	Often the same thing as above: more reduction, like a low first gear	5.13 is lower than 4.10 in this sense
Numerically lower ratio	Smaller number, less reduction, lower cruising rpm, better economy	3.21 vs 4.10
Taller gearing	Less reduction: the same rpm gives more speed. Bigger tires do this too	3.73 with 35-inch tires

Ask any shop which way they mean before you order a set. This page uses "numerically higher" for the bigger number, so there is no guessing.

Whichever word you use, the physics is the same: more reduction means more torque at the wheels and less speed per engine rpm.

How bigger tires change your gearing

A taller tire covers more ground per revolution, so it acts like a taller gear. West Coast Differentials puts a swap from a 30-inch to a 35-inch tire at about a 17 percent change in final drive and says it can drop the engine out of its power band.

The fix is a regear. Their formula is new tire height ÷ old tire height × current ratio.

The result rarely lands on a ratio that exists. Take it as a starting point and round to the nearest set your axle offers.

Current setup	New tire	Calculated target	Taller by	Nearest common ratio
3.21 with 31-inch	33-inch	3.42	6%	3.42
3.55 with 31-inch	35-inch	4.01	13%	3.73 – 4.10
3.73 with 31-inch	33-inch	3.97	6%	4.10
3.73 with 31-inch	35-inch	4.21	13%	4.10 – 4.56
4.10 with 33-inch	35-inch	4.35	6%	4.56
4.10 with 33-inch	37-inch	4.60	12%	4.56 – 4.88
4.56 with 35-inch	37-inch	4.82	6%	4.88

Heavy rigs, automatics and trucks that tow lean toward the numerically higher choice. Weight from bigger tires and a heavier bumper or winch pushes the same way.

Regearing is not the only side effect. Jeep warns in the 2012 Wrangler owner’s manual that tires of a different size may cause false speedometer and odometer readings. Check the readout with our tire size calculator before you trust it.

Moving up one tire size is a smaller step than two or three, and the numbers above show how fast it adds up.

Engine rpm at highway speed

The standard formula is engine rpm = mph × axle ratio × 336 × top transmission gear ratio ÷ tire diameter in inches. The 336 comes from unit conversion: 63,360 inches per mile ÷ 60 minutes ÷ π.

The table assumes a 1:1 top gear at 65 mph. Multiply by your top gear for an overdrive transmission: a 0.75 overdrive cuts every figure by a quarter.

Axle ratio	31-inch	33-inch	35-inch	37-inch
3.42	2,409	2,263	2,134	2,019
3.73	2,628	2,469	2,328	2,202
4.10	2,889	2,713	2,558	2,420
4.56	3,213	3,018	2,845	2,692
4.88	3,438	3,230	3,045	2,881
5.13	3,614	3,395	3,201	3,028

A rig that cruises at 3,000 rpm instead of 2,300 burns more fuel and makes more noise, but it stays in its power band when it climbs. That is the trade you are making when you regear for big tires.

Crawl ratio: first gear × low range × axle

The axle ratio is only the last step. Crawl ratio multiplies it by the transmission’s first gear and the transfer case low range. California Jeeper’s crawl ratio guide gives the formula and the examples below. For factory numbers on every 2026 Wrangler build, see our Jeep Wrangler crawl ratio and 4x4 system breakdown.

To see it, multiply the three numbers from your own drivetrain. The tool above does it, and the diagram shows one worked case.

Setup	1st gear	Low range	Axle	Crawl ratio
Jeep TJ, NV3550 manual, 2.72 low	3.83	2.72	4.10	42.7:1
Same TJ regeared to 4.88 (calculated)	3.83	2.72	4.88	50.8:1
Jeep JK Rubicon, 6-speed manual	4.46	4.00	4.10	73.1:1
Jeep JL Rubicon, Jeep Australia figure	n/a	4.00	n/a	77:1 (as published)

California Jeeper's rule of thumb is 40–50:1 for moderate trails and 60–80:1 for technical rock crawling. Treat it as an owner guideline, not a standard. Tire size is not in the formula, but taller tires make the real torque at the ground lower.

Not sure what first gear you are in? Our guide on what gear to be in off-roading covers when to use low range.

Which ratio to choose

Shop guides agree on rough pairings. Offroadium lists 35-inch tires with 4.56 and 37-inch with 4.88 or 5.13. California Jeeper says 4.56 for 35–37 inch and 5.13 for 37 and up. Both describe these as starting points.

Which one you pick depends on tire size first, then on weight and how you drive.

Ratio	Typical use	Trade-off
3.21 – 3.55	Stock tires, highway cruising, fuel economy	Less torque with bigger tires
3.73 – 4.10	Stock to about 33-inch tires, mixed use	Balanced
4.56 – 4.88	35-inch and larger tires, heavy rigs, rock crawling	Higher highway rpm, slightly lower mpg
5.13 and up	37-inch tires and up, extreme crawling	Very high highway rpm; consider a taller top gear

Jeep owners can see the factory ratios for their model in our guides to the 3.6L Jeep JK and the 3.8L Jeep JK.

Before you regear: a checklist

1. Find your current ratio on the axle tag, the build sheet or by counting teeth (use the tool above).
2. Measure your actual tire diameter, not just the label size.
3. Calculate the target ratio, then pick the nearest ratio available for your axle.
4. Count weight, towing and transmission type. An automatic with big tires usually needs the numerically higher choice.
5. On a 4WD vehicle, regear both axles to the same ratio. Shops treat matched front and rear ratios as standard because 4WD locks front and rear together; this is shop practice, not a manual quote, so confirm with your gear vendor.
6. Have an experienced shop set up the gears. Pinion depth and backlash decide how long they last.
7. Plan the speedometer: tire changes and regears both change what it reads on many vehicles, so verify it with GPS.

Gear ratio FAQ

Is a numerically higher gear ratio better?

For torque and crawling, yes. It also raises rpm at highway speed and can lower fuel economy. Choose by tire size and use.

Do I have to regear if I only go up one tire size?

Not always. A 31-inch to 32-inch swap changes the effective ratio about 3 percent. Two inches or more starts to show, especially with an automatic.

What gear ratio is best for 35-inch tires?

It depends on your starting point. A 4.10 axle on 33-inch tires works out to 4.35 for 35s, so 4.56 is the nearest common set. The table above covers other starts.

How do I find my axle ratio?

Look for a tag or stamp on the differential cover or the build sheet. If neither is readable, count the ring and pinion teeth and divide.

Sources: West Coast Differentials differential FAQ; Gear Technology, "The Hunting Tooth and its Effect on Break-In" (Jan–Feb 2021); 2012 Jeep Wrangler owner's manual (tires chapter); California Jeeper crawl ratio guide; Wikipedia, Jeep Wrangler (JK); Jeep Australia Wrangler capability page; Offroadium axle ratio guide. All tables are calculated with the formulas shown.

Related guides

• Wheel Offset and Backspacing for 35s on a Wrangler or Tacoma