Jeep Gear Ratio Calculator

Jeep Gear Ratio Calculator

Optimize your performance after upgrading tire sizes

Recommended Setup

To maintain factory performance, your target ratio is:

Standard aftermarket gear options to consider:

Why Jeep Gear Ratios Matter

When you install larger tires on your Jeep Wrangler, Gladiator, or Cherokee, you effectively change the final drive ratio. Larger tires have a larger circumference, meaning the engine has to work significantly harder to turn the wheels. This leads to a loss in "peppiness," reduced towing capacity, and often puts your transmission in a constant state of hunting for gears.

The Re-Gearing Formula

To restore your Jeep to its original power band (or even improve it for off-roading), you need to change the ring and pinion gears inside your differentials. The mathematical formula used by this calculator is:

New Ratio = (New Tire Size / Old Tire Size) x Current Gear Ratio

Common Jeep Gear Ratios

Tire Size	Daily Driver Ratio	Performance/Off-Road
33 Inches	4.10	4.56
35 Inches	4.56	4.88
37 Inches	4.88	5.13
40+ Inches	5.13	5.38

Benefits of Re-Gearing

• Restored Torque: Get back that "get up and go" feeling at stoplights.
• Improved Fuel Economy: Stops the engine from lugging in high gears.
• Reduced Transmission Heat: Essential for the longevity of automatic transmissions.
• Correct Crawl Speed: Better control when navigating rocks or steep inclines.

function calculateJeepGears() { var oldTire = parseFloat(document.getElementById('oldTire').value); var newTire = parseFloat(document.getElementById('newTire').value); var oldRatio = parseFloat(document.getElementById('oldRatio').value); var resultsArea = document.getElementById('results-area'); if (isNaN(oldTire) || isNaN(newTire) || isNaN(oldRatio) || oldTire <= 0 || newTire <= 0 || oldRatio <= 0) { alert("Please enter valid positive numbers for all fields."); return; } var recommended = (newTire / oldTire) * oldRatio; document.getElementById('exactRatio').innerText = recommended.toFixed(2); // Find common aftermarket gear sets var gearSets = [3.73, 4.10, 4.56, 4.88, 5.13, 5.38]; var options = []; // Logic to find closest matches for (var i = 0; i (recommended – 0.3)) { options.push(gearSets[i]); } if (options.length >= 3) break; } document.getElementById('gearOption1').innerText = options[0] ? options[0] + " (Closest)" : "4.10"; document.getElementById('gearOption2').innerText = options[1] ? options[1] + " (Power)" : "4.56"; document.getElementById('gearOption3').innerText = options[2] ? options[2] + " (Extreme)" : "4.88"; resultsArea.style.display = 'block'; resultsArea.scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }