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Anyone know recommended PSI for OEM 20" Rims w/ OEM BSW Pirelli PZERO All-Season Seal-Inside size 245/50R20 Tires, help please?

4K views 29 replies 9 participants last post by  jongri 
#1 · (Edited)
Upgraded to 2022 20" OEM Pacifica Wheels & had OEM Pirelli PZERO All-Season Self-Sealing Tires Mounted & Balanced on new Rims. Pacifica Owners Manual & Pirelli Tires only refer you to your Pacificas original Door Sticker for recommended Tire PSI which does me no good since mine came w/ 18" Standard Wheels and OEM Pirelli PZERO Tires size 245/60R18 w/ Factory set PSI between 40-41.
Currently my 245/50R20 OEM Pirelli Tires set between 36-37 psi. Help please & Thank you?
 
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#4 ·
Check the door sticker on the side of the drivers side door. Mine has recommended PSI posted on a sticker. You can also look at the sidewalls and it should state maximum PSI. Usually about 5-8 below that or at least 32 PSI will keep everything happy (TPMS monitors). My PSI states 36 on the door for 20 inch rims. I run 33-36 and it's fine. I do believe the previous poster is right that the PSI rating is the same for 18 or 20 inchers. I wouldn't worry too much if it's within the max range of the tires and the minimum range for the TPMS sensors.
 
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#5 ·
Yeah my Door Sticker gives Tire pressure for my original standard 18" Wheels with 245/60R18 so that's no help since I upgraded my Pacifica's standard 18" Rims to OEM 20" w/ tires size 245/50R20. Thanks for the 33-36 psi for the 20" Rims on yours, much appreciated. I should be okay then where I set mine at 36-37 psi. Thank you again for your assistance with this you guys are awesome!
 
#8 ·
I'm not sure, but I think it has more to do with weight than it does the tire size. Most passenger vehicles are mid thirties, and HD trucks are much higher. My Bronco is 39, and I think that is because it is a heavier vehicle, can't remember what my silverado was. I like to run pressure on the high side for performance, wear, and gas mileage. You can never go wrong running just a few PSI under the max on the tire, except it might be a bit slipperier in adverse conditions. ;)
 
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#13 · (Edited)
36 PSI is the magic number.
Adjust for seasonal weather changes!!!

36 takes into account rolling resistance, ride quality, handling, longevity, etc.
Thank you VelvetRedAWD, much appreciated. I was only getting 15 mpg (All Stop & Go driving) w/ my Factory 18" Wheels PSI set between 40-41. Now with 20" Wheels (All Stop & Go driving) PSI set between 36-37 I'm getting 17 MPG?
36 PSI must be the Sweet spot as you stated for sure for both 18" Wheels w/ 245/60R18 tires or 20" Wheels w/ 245/50R20 tires on AWD Pacificas!
 
#11 · (Edited)
Awesome thanks GM Freak. Believe it or not I'm getting better MPG with the 20" Wheels than I was getting with the Factory 18" Wheels by 2 MPG? Factory 18" Wheels (All Stop & Go driving) 40-41 psi I was getting only 15 mpg?
Now with 20" Wheels set between 36-37 psi (All Stop & Go driving) I'm getting 17 mpg, go figure! Must have something to do w/ the Factory 18" Wheels PSI setting of 40-41, which was too high, my guess?
 
#28 · (Edited)
One trip won't make a difference. You'll have to wait a while to see a true difference if you really track MPG including seasonality. It's contrary in many ways to logical fuel economy rules except one. A 20" has a lot less sidewall so energy wasted compressing the sidewall on turns, bumps, acceleration, compared to using 18" tires, is reduced with a 20".

Everything else seems contradictory. Running higher psi on 18" means the tire sidewall is harder and less energy is lost so that higher psi had no bearing. Going to a 20" is a stiffer sidewall so even if you are 36psi the sidewall is so much harder the psi is just noise in the data. I assume the 20's are wider which should mean more rolling resistance not less. (you can look up rolling resistance on old and new tire to see if there is a drastic difference). I assume the 20" wheels and tires are heavier increasing unsprung weight than the 18"s so improvement in mpg is again counterintuative. Also, normally, like for like, a new tire gets a little worse mpg than an almost worn tire ( less tread depth means less tire squirm in the tread blocks and therefore less energy lost on a worn tire), a taller (new) tire goes faster at the same rpms because it's bigger circumference covers more ground, and air resistance increases the faster you go. A worn tire has less tire squirm, more energy goes to moving you forward, is shorter so at a given rpm it is covering less ground so you are slower and less air resistance.

Taking all this into account the change in sidewall (-1", just the lower side of rim as it's the side flexing) might have something to do with the improvement but there is also a lot of reasons why it shouldn't. Interesting observations on your part. I used to spec gearing for fuel economy on truck fleets and they would always complain about their engine mpg dropping suddenly and it was almost always after getting new tires on the trucks. Also a 245/50R20 is .54" taller than a 235/60R18. Over 1/2" taller tire means you are going a little faster when the speedo says 55 mph compared to the old worn 18" tires when the speedo said 55 mph. If this improvement is seen over more than a few fillups, you have a very positive side effect to getting 20's but it doesn't make sense. In any case, I wonder if I can convince my wife we need to switch to 20's now to save fuel?
 
#12 ·
One thing to remember that hasn't been mentioned is that I believe you need to get the speedometer recalibrated. Someone correct me if I'm wrong with these vans Not sure if the dealer can do it or not either. But the bigger tires will cause your speedometer to be off, at least in my experience. By how much I couldn't tell you. Even 1mph can make a difference to the police though lol.
 
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#14 ·
Never even thought of needing to get Speedometer calibrated for 20" Wheels verses original 18" Wheels. I'll call my CJD dealer & make an appointment ASAP. Many thanks to all commenting here for your invaluable wisdom & input, appreciate you all!
 
#16 ·
Pacificas come with 42PSI from the factory- to prevent flat spots when parked for extended periods of time on the lots. My dealer didn't bother to lower the pressure before the delivery, and I'm still running 42 PSI. I like a bit firmer ride, the wear seems to be better. PacHy is heavier too.
 
#24 ·
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.
 
#25 · (Edited)
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:).
 
#26 ·
Wheel Tire Car Vehicle Window
Wheel Tire Land vehicle Car Vehicle

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