Axle ratio and towing: how much the gearing is worth
Choose a vehicle and a model year: the tool lists its ratings by rear axle ratio and names the ratio that tows the most.
2027 Ram 1500: best axle ratio for towing
3.92 axle
| 3.21 axle | 6,330 lb to 8,430 lb |
| 3.55 axle | 7,330 lb to 8,580 lb |
| 3.92 axle | 7,300 lb to 11,530 lb |
Compiled by Radif Partners · Sources and method · makers’ towing documents read October 20 to 21, 2026
The rear axle ratio is the number of driveshaft turns for one turn of the wheels. A numerically higher ratio, such as 3.92 rather than 3.21, multiplies the engine's torque more and lets it pull a heavier combination from a stop and up a grade, so makers give it a higher trailer rating and usually a higher GCWR. The effect is large when the engine stays the same. On the 2027 Ram 1500 with the 3.0L Hurricane, the 3.21 axle tops out at 8,430 lb and the 3.92 axle at 11,530 lb. On the F-250 with the 6.8L gas V8, the 3.73 axle reaches 14,800 lb and the 4.30 axle 17,300 lb. Across different engines the ratio tells you little: the F-250 diesels reach 22,000 lb on a 3.31 axle. Compare ratios only within one engine, and read the ratio of your own truck on its window sticker.
What the ratio does
The ring and pinion in the rear axle reduce the driveshaft speed before it reaches the wheels. With a 3.92 ratio the driveshaft turns 3.92 times for each wheel turn; with 3.21, 3.21 times. The higher number gives more pulling force at the wheels for the same engine torque, at the cost of higher engine speed at highway pace and, usually, more fuel used when the truck runs empty. In the makers' tables the gain shows up first in the GCWR of the combination, and the trailer rating follows from it.
Same engine, different axle
The table lists every engine that the latest tables of three trucks offer with more than one axle ratio, with the range of ratings each pairing reaches. The other differences in the row, such as drive, cab and package, still play a part, which is why each cell is a range.
| Vehicle | Engine | Axle | Lowest | Highest | Rows |
|---|---|---|---|---|---|
| Ram 1500 | 3.0L Hurricane twin-turbo I6 | 3.21 | 8,310 lb | 8,430 lb | 3 |
| Ram 1500 | 3.0L Hurricane twin-turbo I6 | 3.55 | 8,070 lb | 8,270 lb | 3 |
| Ram 1500 | 3.0L Hurricane twin-turbo I6 | 3.92 | 11,170 lb | 11,530 lb | 6 |
| Ram 1500 | 3.6L Pentastar V6 eTorque | 3.21 | 6,330 lb | 6,550 lb | 3 |
| Ram 1500 | 3.6L Pentastar V6 eTorque | 3.55 | 7,330 lb | 8,100 lb | 4 |
| Ram 1500 | 5.7L HEMI V8 | 3.21 | 8,270 lb | 8,270 lb | 1 |
| Ram 1500 | 5.7L HEMI V8 | 3.55 | 7,990 lb | 7,990 lb | 1 |
| Ram 1500 | 5.7L HEMI V8 | 3.92 | 8,890 lb | 11,370 lb | 3 |
| Ford F-250 Super Duty | 6.7L V8 H.O. Turbo Diesel | 3.31 | 18,200 lb | 22,000 lb | 10 |
| Ford F-250 Super Duty | 6.7L V8 H.O. Turbo Diesel | 3.55 | 18,200 lb | 22,000 lb | 11 |
| Ford F-250 Super Duty | 6.7L V8 Turbo Diesel | 3.31 | 15,500 lb | 22,000 lb | 19 |
| Ford F-250 Super Duty | 6.7L V8 Turbo Diesel | 3.55 | 18,200 lb | 22,000 lb | 11 |
| Ford F-250 Super Duty | 6.8L V8 | 3.73 | 13,800 lb | 14,800 lb | 10 |
| Ford F-250 Super Duty | 6.8L V8 | 4.30 | 16,300 lb | 17,300 lb | 10 |
| Ford F-250 Super Duty | 7.3L V8 | 3.73 | 16,400 lb | 18,200 lb | 17 |
| Ford F-250 Super Duty | 7.3L V8 | 4.30 | 18,200 lb | 18,200 lb | 10 |
| Ram 2500 | 6.4L HEMI V8 | 3.73 | 14,520 lb | 15,640 lb | 24 |
| Ram 2500 | 6.4L HEMI V8 | 4.10 | 10,530 lb | 17,840 lb | 26 |
Three patterns stand out. On the Ram 1500, the weakest 3.0L Hurricane row on the 3.92 axle still beats the best one on the 3.21 axle by 2,740 lb (Ram chart). The chart shows how: the 3.92 rows carry a GCWR of 17,000 lb, against 13,900 lb for the 3.21 and 3.55 rows. The 3.55 axle, oddly, does not beat the 3.21 (8,270 lb against 8,430 lb at best), because its rows are 4x4 while the 3.21 rows are 4x2: same GCWR, heavier truck, lighter trailer. On the F-250, the 6.8L gas V8 gains 2,500 lb at the top with the 4.30 axle. On the Ram 2500, the 6.4L HEMI on the 4.10 axle spans 10,530 lb to 17,840 lb, with the Power Wagon at the low end, while the 3.73 axle stays between 14,520 lb and 15,640 lb.
Check the top rating and its configuration
2026 Ford F-250 Super Duty maximum towing capacity
22,000 lb
| Reached by | 6.7L V8 H.O. Turbo Diesel · 4x4 Crew Cab 6-3/4 ft · 3.31 axle · F-250 High-Capacity Axle Upgrade Package (535) |
| Lowest rating printed | 13,800 lb (6.8L V8 · 4x4 Crew Cab 8 ft · 3.73 axle) |
| Configurations in the table | 98 |
| Source | 2026 Ford RV & Trailer Towing Guide, p. 20-21, 26 |
Why ratios do not compare across engines
A diesel with a numerically low ratio can outpull a gas engine with a high one. Ford's 2026 guide rates the F-250 diesels up to 22,000 lb on both the 3.31 and 3.55 axles, while the 7.3L gas V8 stops at 18,200 lb even on its 4.30 axle. The diesel's torque does the work the gearing does on the gas engine. So "get the highest ratio" is advice for choosing between axles behind one engine, not a rule for comparing trucks.
When the ratio changes nothing
Some ratings ignore the axle altogether. Ford prints 5,000 lb for every 2026 Explorer, on 3.31, 3.58, 3.73 axles alike, which is also the rating of its receiver, 5,000 lb. At the top of the F-250 range, both diesel ratios reach the same figure, equal to the 22,000 lb receiver rating Ford prints. And some documents do not split by axle at all: the Silverado 1500 table we read lists engine, drive, cab and package, with no axle column, so the tool shows nothing for it. Toyota's product information sheets do the same for all five Toyota models: they split the ratings by grade, cab, bed and drive, never by axle ratio.
Finding your own ratio
The window sticker and the build sheet list the axle ratio, often next to a limited-slip or locking differential option. On a used truck, the maker's customer service can usually read the build record from the VIN. Once you have it, open the vehicle page, such as the Ram 1500 or the F-250, and read the row that matches. A ratio swap after purchase does not change the rating on paper: the maker's figure belongs to the factory build. The GVWR and GCWR page explains the combined limit the ratio mainly acts on.