Owning a Jeep can quickly become a lifestyle that can mean much more than just driving. Own one long enough, and you will notice that Jeeps are highly customizable, and owners, hardcore or otherwise, will often do just that to add to its function and personal style.
Whether or not you even plan on customizing your Jeep, if you talk enough Jeep talk with other owners, you will no doubt end up in a discussion about proper gear ratio and tire size. Understanding it is important, even if you plan on doing something simple like changing your Jeep’s tire size or upgrading to a manual transmission..
Short Gear Ratio vs Long Ratio
Your Jeep’s drivetrain comes geared from the factory to provide a balance between torque and top highway speeds. The higher numbered gears are considered short, while the lower numbered gears are long.
Long gears get you higher top speed at lower RPM, while short gears give you a lower top speed but faster acceleration.
When it comes to using your Jeep wrangler for off-road applications, the shorter gears give you lower-end torque.
For example, if you are doing some rock crawling, it is going to be those short gears that will provide more torque and less overall speed than long gears at the same RPM, meaning you can use the RPM to your advantage to slowly get over an obstacle. On the other hand, the longer gears allow for better fuel mileage and best fuel economy when cruising, resulting in a higher top speed at a lower RPM.
Jeep Gear Ratio tire size Chart
Below is a gear ratio chart that you can use to determine the best gearing for your Jeep for the situation or situations in which you intend to use it.
Jeep Wrangler Gear Ratio Identification
Depending on the year and model of your Jeep Wrangler, it may have one of several gear ratios. Here are a few ways to be able to identify what ratio your Jeep wrangler may have, including the ratio for the manual transmission.
Diff Cover Tag
Jeeps all come with a diff cover tag that easily identifies the ratio, which might be the easiest way to identify your proper gear ratio. There is always a chance that that tag might be missing, though. Keep in mind that this is the factory gear ratio. If you are not the original owner, there is a possibility that the gears have been changed.
A jeep build sheet for your Jeep should be easily attainable from your local dealer if you don’t already have one. While not always accurate since gears can be changed, it’s a good place to start.
Counting Driveshaft Revolutions
If still unsure after checking the diff tag, or the build sheet, you can jack up the rear end of the Jeep. With the Jeep in neutral, have someone turn the wheel two complete revolutions while you count how many times the driveshaft turns. This number will be your proper gear ratio. Three rotations of the driveshaft would be a 3.07 gear ratio, three- and three-quarter rotations would be a 3.73 gear ratio, and so on.
This one is a little more labor-intensive and should probably be an option when you’ve exhausted all others. For this, you have to jack up the Jeep and open the diff cover. And if you don’t have jack then you will have to pay cost to lift a jeep. At this point, you should be able to see the teeth of the ring and pinion gears. Count both the ring and the pinion teeth. Then, divide the number of ring teeth by the number of pinion teeth, and you will have your ratio.
Whether you want to customize your Jeep or only understand better what your factory Jeep is capable of, the gear ratio and tire size (tire diameter) plays a big role. If you plan on your jeep being a daily driver, hitting the open highway, you’re not going to want a Jeep that has been geared longer for off-road use and vice versa.
People Also Ask
Figuring out the right gear ratio and tire size for you, or even trying to figure out if you need to regear your Jeep to suit your needs, there is no doubt you will have some questions. Here are some that we get asked most frequently.
Yes, bigger/ Larger tires size will decrease the effective gear ratio (longer ‘gears’) in your Jeep. Increased tire size means that the tires rotate slower to cover the same amount of ground. Larger tires size chart explains it more in depth.
Which gear ratio is better to have is dependent on how the Jeep is being used. A lower-numbered gear ratio (longer gears) will be better for highway cruising and commuting while a higher numbered gear ratio (shorter gears) is better suited for off-road applications where higher torque is needed or for better acceleration.
A higher-numbered gear ratio (4.10:1 for example) means that your Jeep has shorter gears more suitable to lower speeds at higher RPM.
Gear ratios do not directly affect horsepower as far as numbers are concerned, but instead, determine how and where that horsepower is used. Also, Gear ratio do affect towing power.
The cost of regearing your Jeep will depend on the shop you chose to do it as labor rates can vary considerably from shop to shop. With that being said, done properly, you can expect to spend $600 to $1200, without changing the differential carrier.
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