Not enough info to go on. Did you swap for same size tires? Different size? What prompted you to check your speedometer accuracy?

Anyway, use a programmer like jscan or AEV procal and input your actual tire size and you should be good to go.

If it’s still off then something else is wrong. Bad speedo?

 

That's a big discrepancy. I purchased an app called JScan and a dongle that plugs into the OBDII port under the dash. Also allows tire pressure settings change to allow lower tire pressures without the warning light coming on.

 

I have a better question, where can I take it to get it calibrated?

 

Most places can’t or won’t make the adjustment unless you supply them with the programmer. When you use the programming tool the first time, it records the VIN of the Jeep and then cannot be used on a different Jeep unless it connected to the original Jeep and all settings are reset to factory.

The tools are so easy to use, it really isn’t worth it to pay someone to do it for you.


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10mph variance suggests a pretty significant change in tire size

 

The dealer can reprogram your Jeep for larger tires. But I would not take it to the dealer, personally. But that is up to you.
I would either go with the Jscan app and a dongle or go with the AEV ProCal. I use a ProCal, in part because it is pretty simple to use. But either way, ProCal or Jscan, I prefer doing it myself. That way, down the road, if I need to change the settings again I can.

 

Im afraid I mess something up. Im not very electronic savvy

 

I bought a programmer.

 

That one seems complicated compared to the Jscan app. Find the tire size screen and scroll through to the inches and quarter inches settings and you're done. So my 33" tires which are 32.6 are set at 32.5" up 1/2" from my stock tires. It was like setting a timer on a smart phone and saving.

 

Just getting the blue tooth connection between the Jscan app and the blue tooth widget you plug into the Jeep is harder then setting a few dip switches for a guy like me.

 

I do not have huge tires but I changed them out and would like to have the speed correct.

Can you let us know what tire size you change from and the size of the new tires?

 

I use the superchip programmer. It was really easy. I would recommend it.