3.31 vs 3.55 Axle Ratio: Difference Between 3.31 And 3.55

It’s a matter of numbers and purpose. When your truck is empty and you are not towing, there is little difference between these two axle ratios. But when you are towing, you will see a slight difference between the two axle ratios.

One of the differences between these two axle ratios is the fact that the 3.55 tows more weight than the 3.31. You are looking at about a 1200-pound difference and that is due to the 3.55’s increased torque and acceleration.

To learn more about this topic, just continue to read our article. It has the information you want to know about so you can make an intelligent purchase decision. Take a few minutes to see how this information can help you.

Difference Between The 3.31 And 3.55 Axle Ratio

The first difference has already been explained. The 3.55 axle ratio can tow more weight than the 3.31 axle ratio. But this does not mean the 3.55 is a superior axle ratio in all categories.

The 3.31 excels when it comes to fuel mileage. It can help you get between 1/2 and 1 extra mile per gallon due to drive shaft revolutions. But if you are hauling heavy weight, that extra fuel mileage may not be a big benefit when the 3.31 drags a bit more than the 3.55.

In addition to being able to tow heavier loads, the 3.55 has better torque than the 3.31. The more torque, the higher the RPMs you will get. This boost makes climbing hills a lot better with the 3.55 than with the 3.31.

As for acceleration, this category is also won by the 3.55. The reason for this victory is that the 3.55 has more revolutions per minute than the 3.31. These are significant differences to many trailer owners as they are looking for more power to tow their trailers up those steep inclines.

Is 3.55 Gear Good For Towing?


Well, you can say both axle ratios are good for towing, it is just that the 3.55 is better. The reasons have already been explained why this is so. The 3.55 puts more power into those rear wheels which helps you drag that trailer up those mountain slopes.

Plus, you get better acceleration so you won’t be that sluggish off the line. You should be able to get a good start so the drivers behind you won’t get too upset for being slower than they would like.

On top of that, you should be able to tow about 13,900 pounds with this axle rating. The 3.31 is no slouch either as it can tow about 12,700 pounds. Of course, there are other factors involved when it comes to towing. One is the type of engine you have under the hood.

Another would be if you have the tow package or not. Towing is not all about the axle ratio. That part is just one component out of many that make towing heavier weights easier.

When you are hauling tools that weigh over 250 pounds combined and other equipment, it is better to go with the 3.55. The extra power can haul that weight easily.

What is a 3.55 Axle Ratio Good For?


One thing it is not good for is better gas mileage over the 3.31. It may get better gas mileage than the 3.73 or the 4.10 but those axle ratios are not being compared with this one in this article.

As you may know, the axle ratio means that the drive shaft spins faster than the axle does. It will spin 3.55 times compared to the tire's one rotation. While this is good for when your truck is working it is not that good for gas mileage.

If gas mileage is very important to you, then you should go with the 3.31. The 3.55 is good for towing, hauling, and accelerating and it is good for heavy weights. You can haul or tow a lot more with the 3.55 added to your overall truck package.

If you use Ford’s build-a-truck web page system, you will find that if you go with the 3.55 you will need to upgrade to heavier springs. Both parts will increase your overall costs.

Some dealers will say their version has you upgrading to 20” tires but that may not be so. Be careful when working for the dealer as they will squeeze every dime out of you that they can.

But if you are hauling or towing heavy weights constantly, then the 3.55 is the way to go.

What Axle Ratio is Better For Mileage?


The 3.31 is better for gas mileage. But that difference is not really that significant on a gallon-by-gallon ratio. The best you can get is between 1/2 to 1 mile per gallon over the 3.55.

That is not a lot of extra fuel until you factor in the total number of gallons in your fuel tank. If your truck has a 40-gallon tank, just as an example, you could possibly get 20 to 40 extra miles down the road.

On long trips that is a significant fuel saving. The thing is, you only need the 3.55 if you are going to tow extra heavy trailers or large items that weigh a lot. The 3.31 can do the same job as the 3.55 but at a lower tow weight capacity.

The lighter the weight plus the 3.31 axle and you may see some good fuel savings after your trip is over. Of course, if you are going to go over mountain passes, then the savings may not be there as the power is not going to be there either.

Your purchase decision will have to factor in the weight of your trailer, your cargo, and your passengers’ weight to figure out which option would be best for you.

Is a 3.31 Or 3.55 Axle Ratio Better?


Both are good and to determine which one is better, you have to look at your driving purpose. The biggest benefit you get from the 3.55 is towing and hauling heavier loads, better torque, and more acceleration.

This is good for those 30 to 45-foot trailers or 5th wheels that exceed 10,000 pounds. The 3.31 can handle those heavier and longer trailers but only up to almost 13,000 pounds, the 3.55 goes beyond this figure.

When your trailer is longer and heavier, the 3.55 is the better way to go. If your trailer is shorter and lighter than 10,000 pounds, then the 3.31 is the better option. You do not need all the power the 3.55 provides and technically, there is little difference between the two axle ratios.

If your fuel mileage is the deal breaker, then the 3.31 is the better axle rating. You do get more mileage out of this axle ratio if you are not a crazy driver and have some bad driving habits.

Like towing, the axle ratio is only one component that influences your actual mpg. You may find that for those lighter trailers, the 3.55 is best for you. Test drive both to see which one you like the most.

F150 And F250 3.31 vs 3.55 Axle Ratio


When people go out to buy a new truck, they often overlook this important factor. The axle ratio is often left out of the discussion as most people do not understand its contribution to your towing and driving needs.

Which axle is best for these truck models depends on your purpose for the trucks. For example, if you are merely using the truck to be your daily driver and do a few odd hauling jobs, then the 3.31 is better for you.

If you are towing and hauling heavy weights constantly, then the 3.55 is the best option to have in your truck. One thing we did not mention above is the speed factor.

With the 3.31 you have to be going 80 before you can drop the transmission into 10th gear. With the 3.55, you will hit the 10th gear by about 50 mph. If you want and need speed then the 3.31 is the axle ratio to go with.

You have to look at all the factors involved before you make up your mind about which one is the best for your living situation. Both axle ratios are good and both excel when they are used for the right purposes.

Some Final Words

Technically, the two axle ratios are about the same. Each one has benefits for different purposes that make one better than the other and vice versa. To pick one, you have to look at what you need from your axles.

If it is speed and gas mileage, then go with the 3.31. If it is towing and hauling, then go with the 3.55. You are not losing out if you pick one over the other, you are just getting the best axle for your specific purpose.

The mistake would be picking the wrong axle for the wrong purpose.

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