[jongri]

No calibration should be needed.
A 245/60R18 is 29.6" overall.
A 245/50R20 is the same 29.6" overall, meaning there will be no affect on the speedometer because the overall diameter is the same.
View attachment 52236


Gotta remember, adjusting wheel size doesn't mean overall diameter has to change.

Awesome diagram you provided here Cool Minivan..... Nobody. Appreciate your input to this post. To be safe I'll have my Chrysler dealers service check calibration anyway and adjust as needed (especially since I have the New Maximum Care Extended Warranty & don't want to risk having it voided). Paying a few $ for them to check everything w/ the 20" wheels & tires is in my best interest. Thanks again for submitting this Wheel Size/Speedometer error comparison Chart.

 

[Cool Minivan..... Nobody]

Awesome diagram you provided here Cool Minivan..... Nobody. Appreciate your input to this post. To be safe I'll have my Chrysler dealers service check calibration anyway and adjust if needed. Thanks again for submitting this Wheel Size/Speedometer error comparison Chart.

I mean they'll gladly do it whether it needs to be done or not, they like taking people's money to do nothing.

 

[stop-eject]

Keep in mind that firmer tires transfer more road irregularities to the ball joints, bushings and struts.

I'm trying to pick better roads

 

[6Gen]

You do not need to recalibrate the speedometer. Check it vs. GPS (phone navigation app) while driving at highway speeds.

Oh, and thinking you've measured vehicle's typical mpg - based on a 79mile sample run, straight out of the factory and including associated idle time, nor with a minimum 500mi break-in period - is purely speculative.

 

[jongri]

Thanks for your invaluable input 6Gen and awesome overhead avatar of your Pacifica, unique for sure! I'll try checking (my iPhone Nav App vs GPS) if I ever get on a highway that is, as you've suggested.
Also I'm in total agreement w/ you & everyone else commenting here as far as my 79 mile observation (Me & my big mouth so to speak - Wish I hadn't posted it honestly, lol).
My new 2022 Pacifica AWD had 36 miles when I bought it from dealership. My salesman took the time (over 3 hours) showing me how to use everything (including Uconnect 5 Nav 10.1 Touch Screen Display, Instrument Panel, Stop & Go, Uconnect Theater Family Group w/ all included features, Sunroof, Stow & Go Seats, Stow & Vac, pairing my iPhone Pro Max & iPad Pro, etc.) as well as resetting my Average Gas Mileage before I left dealership lot for first time.
So the initial 36 vehicle miles from factory to dealership wasn't included in my OEM
18" Rims 79 miles mpg observation. However, you'll get no argument from me concerning the 79 mile mpg observation as being mere speculation for sure.

 

[jongri]

(Left)18" Wheels w/ OEM BSW 245/60R18 (Right) 20" Wheels w/ OEM BSW 245/50R20

 

[jongri]

I mean they'll gladly do it whether it needs to be done or not, they like taking people's money to do nothing.

Cool Minivan.....Nobody is correct. My C-J-D Dealers Service called to say no speedometer calibration was needed b/c there's really no difference between the 18-Inch & 20-Inch Wheels. Thanks again Cool Minivan.....Nobody & everyone else here for your great advice! Much appreciated.