How to choose the right axle ratio for the best pickup truck performance
Axle ratio. It’s one of those techy optional items buyers of new pickups ask questions about a lot. Probably more so than tow ratings and engine options.
That’s because manufacturers don’t think informing buyers about axle ratio options helps sell their trucks or plays into a buyer’s ultimate decision making process.
So there’s very little, if any, axle ratio information in their brochures or on their websites.
But choosing the right axle ratio does make 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 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.
HWT insights: Axle ratio advice from Ford, Ram and GM
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.
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 quicker 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.
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 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.
