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2015 Tundra towing_BS21060Lots of options, but choosing the right one is important; don’t let the salesman lead you astray on making the best choice

Axle ratios. What to do?

Choosing the right axle ratio makes a difference in how a pickup performs, be it empty, towing a trailer or hauling a heavy load in the bed. Axle ratio also affects fuel economy on the open highway.

So when you get ready to buy your next new pickup truck, make sure you take a little time to decide if the one on the lot has the right axle ratio for your specific work and recreational needs. Spending an extra $200-$350 at the time of purchase could make the difference in how well you like the new truck’s overall performance.

So here’s the short take on how to choose the best axle ratio:

  • FUEL ECONOMY: When it comes to fuel economy, look at the axle ratio as the amount of fuel burned over a given amount of time when the truck is running at highway speeds.

For example, a truck with a 3.31 axle ratio would burn less fuel at highway speeds than one with a 3.55 ratio. That’s because the 3>31 ratio keeps the engine rpm lower than would the 3.55 ratio.

Likewise, a 3.55 ratio would get better mpg at highway speeds than it would equipped with 3.73s – all other things being equal.


Getting the right axle ratio plays a bigger role in V6s and V8s than it does diesels. Smaller gas engines need more gearing help to get loads moving quicker.

How much better mpg? In general, about .5-1.0mpg at 65mph per .25 increase in axle ratio.(It’s important to note that in city driving there’s negligible difference in fuel economy between axle ratios.)

  • PERFORMANCE: The larger the axle ratio number, the faster the truck will accelerate. For example, a truck equipped with 3.55:1 axle gearing will accelerate faster than one equipped with a 3.31 axle ratio.

Similarly, a pickup with a 3.73 axle ratio will be faster than one with 3.55s. It does’t matter whether the truck is empty or loaded. It’s pure mechanics.

  • BEST TOWING RATIO: In general, the best towing axle ratio for most of the post-2010 pickups is in 3.55 or 3.73. Those ratios provide very good acceleration with gas V-8s and diesels. (Heavy-duty diesel pickups can usually get along just fine with 3.31 or 3.55 ratios unless towing loads more than 10,000 pounds.)

Trucks equipped with 8-, 9-, or 10-speed automatics may work well with 3.31 ratios as the new transmissions have lower 1st and 2nd gears than the old 4-, 5- and 6-speeds, helping offset the axle ratio acceleration deficit.

  • BEST MPG RATIO: If getting the best fuel economy is priority, then choose the lowest numerical number offered, such as 3.08, 3.23 or 3.31. This applies only to highway driving; city driving mpg isn’t really affected by the axle ratio. If you do a mix of both, go with the “standard” axle ratio offered by the manufacturer.

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