Everything You Should Know About Jeep Speedometer Calibration For Larger Tires

A Jeep speedometer calibration for larger tires is important after performing some cosmetic modifications to your vehicles. 

These modifications may add some weight to your Jeep, which is why a calibration is necessary since it takes into account your tire size, gearing ratio in your drive cable, as well as the driving ratio in differential. These all have an effect on your speedometer’s accuracy.

So, if you are looking to perform this task, keep reading to have a better understanding of what to expect. Find out what the benefits of a speedometer calibration is and everything else that it entails.

jeep speedometer calibration for larger tires

All About Jeep Speedometer Calibration for Larger Tires

As we have stated earlier, it is important to do some calibration after performing cosmetic changes that incorporate additional weight to your vehicle.

There is a decrease in the accuracy of your speedometer when you alter the tire size. This happens because with just a single, complete axle turn, this results in a complete revolution to your stock tires. However, aftermarket tires that are larger, a complete axle rotation leads to a reduction in the distance covered.

With this in mind, you need to accelerate more. Also, the speedometer will read higher speeds even if you drive at a lower speed. Keep in mind that speed is the distance value that you have traveled, then divide this by time. The speedometer measures the distance traveled by your tire rotation. And because of the alteration that your bigger tires have caused, the speedometer may end up reading lower.

Moreover, the driving ratio in your differential refers to the throttle response’s reaction when braking or accelerating. Because of this additional weight on your vehicle, the throttle response becomes slower. There is also an effect of how your speedometer calculates speed because of the weight change, which also leads to a faulty driving ratio.

Effects Of Uncalibrated Speedometer

If you decide to not do a speedometer calibration and then drive your vehicle, you run the risk of getting an overspeeding ticket when driving on the highway, in case you have gone over the speeding limit.

With an inaccurate speedometer, and you drive at a higher speed that what is indicated in your speedometer, then this is a case of overspeeding. 

Additionally, there is a chance of losing control when you drive. This typically happens among new drivers who are accustomed to checking their speedometer to determine their driving speed. 

When you drive, it is important to consider certain needs, particularly when you are driving in a poor weather condition or when you are cornering. When you drive at a greater speed during these conditions, you may end up losing control of your vehicle. This is common with Jeeps that have an uncalibrated speedometer that may state they are still at a low speed.

Thus, you need to determine if your speedometer is functioning properly. You may want to drive at a highway or a road with markers. Then, have someone measure the time for the distance you have traveled.

Keep in mind that these markers indicate distance between each marker. You need to drive at a specific speed and make sure that your speedometer reads constantly for the entire duration of your drive.

After your drive, divide the total time that covered the distance these markers indicated, so you can obtain the average speed. When your total average speed is not the same as the speed shown in your speedometer when you drive, then you should get your speedometer calibrated.

But if there is only a slight difference, you don’t have to worry since there are always some minor discrepancies. 

How To Do A Jeep Speedometer Calibration For Larger Tires

When you have bigger tires, you need to think about common effects such as speedometer inaccuracy. This is why you need to do some recalibration such as by using a device called Quickcal. This allows you to recalibrate the speedometer quickly and easily, so it matches with your large tires.

This device includes a cable, which you will plug into your OBD II port located on the lower portion of your dashboard. 

When you have plugged the cable in, this turns the device on and then off. Turn your ignition key halfway without starting the engine. 

Afterwards, you will receive a prompt to do some tasks such as clear DTCs and restore, fix your speedometer or show the GPS speed. Choose the option stating to fix the speedometer and then turn your engine on.  Drive at the indicated speed stated on your Quickcal device.

As you drive, you will find that there is a different GPS speed than what is stated on your speedometer. This is why you need to do some recalibration. You will have to choose to apply the current settings on your vehicle but be sure you are at a stop when you do this. 

Next, you can turn the ignition on and press the OK option. Turn the engine off and then press OK. There is some short wait time when uploading the new settings, and you can turn your ignition on and select OK.

This will now result in the clearing of the DTCs, and select OK once you have finished. This will then mean that your speedometer recalibration has completed, and you can unplug this device.

Read More: Odometer Stays On When Car Is Off? What You Can Do

Bottom Line

A Jeep speedometer calibration for larger tires is important to ensure your safety and peace of mind when on the road. This is why we highly recommend that you get this done to prevent any issues along the way and make sure your speedometer is giving accurate readings that it is supposed to do. 

With a simple tool or device, you can perform a speedometer calibration for a few minutes, which should be easy for anyone to do. Then, you can ease your worries knowing that your vehicle is working as it should.

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