I just put 315/70/17s on my truck...... what do I need to do so the Speedo is correct?

 

First, fill out your signature so everyone knows what year, etc. truck you have.

Second, use the 'search' function available on this forum. There's a lot of information about recalibrating the speedometers, and how it can be done via a Snap-On reader tool, a Smarty Jr., or the dealership.

 

Sorry new to this. I am not even sure how to fill the signature out..lol

 

if your running 315/70/17 then you are going 5 mph faster than what speedometer says. 35 mph on meter means 40 mph actual speed. I'am running 317/70/17 right now

 

Bully Dog makes a Speedometer Calibration & Diagnostic Tool. Contact your local Off-Road Shop, It cost me around $100.00. You can also purchase the tool for $640.00 at http://www.xtremediesel.com/bullydog...ostictool.aspx

The Speedometer Calibration & Diagnostic Tool serves two functions:
- Calibrate the OEM in dash speedometer to read correctly with the addition of a larger or smaller diameter aftermarket tire size.
- Read and erase diagnostic trouble codes that appear in vehicles computer when the vehicle has a problem.

Using this tool is simple, it can be operated by anyone who has a general knowledge of tire sizes. To calibrate an OEM speedometer.
1. Plug the OBD II plug into a vehicles OBD II port.
2. Select the correct vehicle application.
3. Enter in the new vehicle tire size.

The whole process takes less than five minutes per vehicle.

ADJUST TO A LARGE RANGE OF TIRE SIZES:
When going up in size the Speedometer Calibration Tool can calibrate for a maximum size of 38" tire diameter. When going down in size it can accommodate for a 26" tire diameter.

 

you can also take it to the dealer to be recalibrated.they did my 02 for free about 5yrs ago.but,they charged me a 1/2 labor to have it done on my 09.nothings free around chrysler anymore.

 

If you have a good service manager like I have, he or she will do most anything to your ECM that you ask. My dealer service manager personally plugged in my truck the day I purchased it and did all sorts of things that I had requested. Did not cost me anything. He let me watch him and even showed me what he was doing. My 2cents worth.