What is Axle Ratio?

When shopping for a pickup truck, many drivers focus primarily on engine, exterior colors, and interior features. While all of those are important, there’s one aspect of a potential new or pre-owned truck you shouldn’t overlook: axle ratio. What is an axle ratio? Axle ratio refers to the gears in a truck’s differential, which connects the rear axle to the driveshaft and then the engine. This ratio expresses a truck’s towing capacity and fuel economy, and the relationship between the two. 

What Does the Axle Gear Ratio Mean? 

The axle ratio is the number of revolutions the driveshaft must make to spin the axle one full turn. This number is shown in the ratio, which represents the number of the ring gear’s teeth divided by the number of the pinion’s teeth. If a truck has an axle ratio of 3:73:1, for example, the driveshaft turns 3.73 times for each full wheel spin. In terms of how an axle ratio should be structured, 3.73 and 3:73:1 are technically both correct and mean the same thing. 

How to Find Axle Ratios 

Here are two ways to find the axle gear ratio of a vehicle: 

• Method 1: Count the number of teeth on the ring gear and the pinion. Divide the number of the ring gear’s teeth by the number of the pinion’s teeth. This will give you the axle ratio. 
• Method 2: Method 1 requires that you take apart your differential, but there many be an easier way. Most differentials on new models list axle ratio on a sticker located on the outside — no need to do any additional work. 

Best Axle Ratios for Trucks

The best axle ratio for your truck depends on your application. Are you looking for a truck with heavy-duty performance? Or, are you more concerned about fuel economy? In any case, the axle ratio matters. 

• Fuel Economy: When shopping for a truck with good fuel economy, regard the axle ratio as the amount of fuel the truck burns while operating at highway speeds for any amount of time. If one truck has an axle ratio of 3.31 and another has a ratio of 3.55, the former will burn less fuel. This is because the first truck’s engine has lower revolutions per minute than the second truck. 
• Performance: Looking again at the ratios used above, the higher 3.55 ratio indicates faster acceleration whether the truck’s empty or loaded. The higher the ratio, the more revolutions per minute. 
• Towing: For pickup trucks released after 2010, the best axle ratio for towing falls somewhere between 3.55 and 3.73. This range provides good acceleration for V8 gas and diesel engines. Many new trucks that have an axle ratio of 3.31 can also be good towers if equipped with 8- to 10-speed automatic transmissions with lower first and second gears. 

Learn More About Axle Ratio at Badger Truck & Auto Group! 

To summarize: What is axle ratio? It’s a ratio that represents the number of revolutions the driveshaft must make to spin the axle one full turn. The higher the ratio, the higher the performance. The lower the ratio, the higher the fuel economy. Do you have additional questions? Contact the truck experts at Badger Truck & Auto Group or visit us in person near Waukesha and Madison!