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Guys- just took delivery of my first jeep - 2020 gladiator. The dealer put a mopar 2” lift with fox shocks, plus 37” nitro ridge grappler tires. The sales manager of course said the calibration of the speedo was taken care of as I was signing on the dotted line. Well, it’s not. I’m going to have to show up at the dealer, because he’s not returning my calls. With the 37” tires, the speedo is reading ~11 mph low at 65MPH. It bothers me, and I don’t know if it’s something that just comes with the territory and live with it. I also don’t know if the transmission shifting is affected-does the computer shift based on MPH or based on RPMs?

My gladiator has the 4.10 gears and max tow package, if that matters at all. Shouldn’t the dealer be able to handle this with a flash tune? If they don’t, then what?

Your thoughts would be appreciated...

Thanks,
Mike
 

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I mean if you literally just bought it go to the dealership. It’s a matter of programming and I believe beyond the speedo adjusts the shift point. You could do it yourself with the right equipment but why bother on a new and very expensive rig.


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The dealer responded, and they will be handling the speedo calibration. I’ve bought lots of other cars from this dealer group over the years, so I’m sure they’ll do me right. Will be curious to see if the shift points change along with it. Thank you for all the info!
 

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The dealer responded, and they will be handling the speedo calibration. I’ve bought lots of other cars from this dealer group over the years, so I’m sure they’ll do me right. Will be curious to see if the shift points change along with it. Thank you for all the info!
I am sure by law they have to handle it. If you your speedo is off that far so is your odometer and 17% off would be substantial. I guess on the bright side it would stretch your 3/36000 warranty out to over 43373 miles and the 5/60000 drivetrain over 72,000
 

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11 MPH is a LOT!

My JL came from the factory with the speedo calibrated to show I was going 2-3 MPH faster than I really was. I checked against several of those electronic readers placed on the side of the freeway. After I swapped the OE 32.1-inch tires with a set 33.2-inch KO2s, the speedo calibration is now pretty accurate.

Hope you get things resolved.

Good luck.
 

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The aftermarket option most everyone with JL's and JT Gladiators are running is the Tazer Lite. Lots of ways you can change settings running it.
 

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Get the Tazer instead. It's slightly more money, but you can use it any time you wish to change tire size, gear ratio, add LED lights to your Sport, winch mode, and a laundry list of other uses. It's worth its weight in gold.
 

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Guys- just took delivery of my first jeep - 2020 gladiator. The dealer put a mopar 2” lift with fox shocks, plus 37” nitro ridge grappler tires. The sales manager of course said the calibration of the speedo was taken care of as I was signing on the dotted line. Well, it’s not. I’m going to have to show up at the dealer, because he’s not returning my calls. With the 37” tires, the speedo is reading ~11 mph low at 65MPH. It bothers me, and I don’t know if it’s something that just comes with the territory and live with it. I also don’t know if the transmission shifting is affected-does the computer shift based on MPH or based on RPMs?

My gladiator has the 4.10 gears and max tow package, if that matters at all. Shouldn’t the dealer be able to handle this with a flash tune? If they don’t, then what?

Your thoughts would be appreciated...

Thanks,
Mike
Get a Tazer JL and do it yourself. Don't rely on the dealership.
 

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JScan, cheapest route and has tons of options. You can recalibrate for less than $90 and it has a bunch of other options as well
 

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11 MPH is a LOT!

My JL came from the factory with the speedo calibrated to show I was going 2-3 MPH faster than I really was. I checked against several of those electronic readers placed on the side of the freeway. After I swapped the OE 32.1-inch tires with a set 33.2-inch KO2s, the speedo calibration is now pretty accurate.
I believe the speedometer being off, is after the mods and tire size changes.
 

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