Speedometer calibration when upsizing to 33"?

Jeepsport75

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I just added Rubicon 33" take offs to my stock 2020 JL Sport S, wanted to know if this will effect shifting by transmission, and if i need to get speedometer calibrated?
I was using my WAZE app and it was showing about a 2 MPH difference from jeep speedo 72/70. does this sound right. Is it needed to calibrate speedometer for tires?





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Strommen95

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Transmission isn't affected by speedometer. Your speed sounds right, there is about a 1-2% margin of error comparing speed with 33 inch tires to stock 31.5 inch tires.

Correcting the speedometer is your choice. Correcting it will do just that, adjust the speedometer on your display. It's not "needed". A Tazer does give many benefits though besides adjusting speed. There's many things you can control with it, disabling ESS is one example so I'd recommend buying one and kill a few birds with one stone.
 
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Htfan

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I just added Rubicon 33" take offs to my stock 2020 JL Sport S, wanted to know if this will effect shifting by transmission, and if i need to get speedometer calibrated?
I was using my WAZE app and it was showing about a 2 MPH difference from jeep speedo 72/70. does this sound right. Is it needed to calibrate speedometer for tires?
With the 8sp auto, Larger tires do impact the transmission's utilization of 8th gear. You will see it less often.
 
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Jeepsport75

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With the 8sp auto, Larger tires do impact the transmission's utilization of 8th gear. You will see it less often.
I have the V6 engine, did notice a couple MPG loss. Would that involve a gear change in rear end?
Thanks
 

Htfan

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I have the V6 engine, did notice a couple MPG loss. Would that involve a gear change in rear end?
Thanks
No gear change needed for 33s. You'll just see 8th less because of the larger diameter/heavier tire. You can still manually get into 8th on the hwy if your auto trans does not do it for you.
 

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I was fine with 33's and it was only off 1-2 mph but when I went to 315/70/17's I did have the dealer recalibrate for 34.5" tires as that was off 5-7mph.
 

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