Axle Ratio Calculator
The Axle Ratio Calculator computes the rear axle gear ratio from ring gear and pinion gear tooth counts. Determine how your axle ratio affects acceleration, towing capacity, fuel economy, and top speed for trucks and performance vehicles.
🕐 Recent Calculations
What is Axle Ratio?
Axle ratio (also called rear-end ratio or differential ratio) is the number of times the driveshaft rotates for each rotation of the axle (wheel). A 3.73:1 axle ratio means the driveshaft spins 3.73 times for every one wheel revolution. Higher ratios provide more torque multiplication at the wheels.
Truck owners choose higher ratios (3.73, 4.10) for towing and acceleration. Highway cruisers prefer lower ratios (3.08, 3.23) for better fuel economy at speed. The axle ratio is determined by the number of teeth on the ring gear divided by the pinion gear teeth.
使用される計算公式・方程式
この計算ツールは5つの主要な公式を使用しています：
1 Axle Ratio Calculation ▼
A ring gear with 41 teeth and pinion with 11 teeth: Axle Ratio = 41/11 = 3.73:1.
2 Engine RPM at Speed ▼
At 60 mph, 3.73 axle, 0.70 overdrive, 28-inch tires: RPM = (60 × 3.73 × 0.70 × 336) / 28 = 1878 RPM.
3 Effective Ratio (with Transmission) ▼
3.73 axle × 2.97 first gear = 11.08:1 overall ratio in first gear.
比率計算ツールの使い方
この比率計算ツールは、以下の3ステップで簡単にご利用いただけます：
数値を入力
入力欄に既知の比率の値を入力します。求めたい未知数の入力欄は空欄のままにしておきます。
モードを選択
比率モード（解く、簡素化、スケーリング）を選択します。各モードで異なる計算式が適用されます。
結果を確認
計算するボタンを押します。結果画面に答えと、視覚的な比率バー、円グラフ、詳細なステップバイステップの解決プロセスが表示されます。
実例問題と段階的な解説
本比率計算ツールを使って、以下の3つの例題をステップバイステップで解決するプロセスです：
入力 1 Ring gear: 41 teeth, Pinion: 11 teeth
入力 2 Compare 3.23 vs 3.73 for towing
入力 3 Engine RPM at 70 mph with 3.55 ratio, 30-inch tires, 0.65 OD
よくある質問 (FAQ)
What axle ratio is best for towing? ▼
For heavy towing (7,000+ lbs), use 3.73:1 or 4.10:1. These ratios multiply engine torque more, making it easier to pull heavy loads and climb hills. The tradeoff is slightly lower highway fuel economy.
How does axle ratio affect fuel economy? ▼
Lower numerical ratios (3.08, 3.23) improve highway fuel economy because the engine turns fewer RPM at cruising speed. Higher ratios (3.73, 4.10) increase RPM at the same speed, consuming more fuel.
How do I determine my vehicle's axle ratio? ▼
Check the door jamb sticker, owner's manual, or RPO code. Alternatively, jack up one wheel, rotate it two full turns, and count driveshaft rotations. If the driveshaft turns 3.73 times, you have a 3.73 ratio.
Can I change my axle ratio? ▼
Yes. Swapping the ring and pinion gear set changes the axle ratio. Common swaps include 3.08 to 3.73 for towing, or 3.55 to 4.10 for off-road trucks. Professional installation and setup is recommended.
What is a limited-slip differential? ▼
A limited-slip differential (LSD) distributes torque between both wheels when one loses traction, unlike an open differential which sends all power to the spinning wheel. The axle ratio remains the same regardless of differential type.