[jongri]

I'm getting better gas mileage by a couple of mpg with the 20" wheels so far at least? May have something to do with setting psi of 20" Wheels 245/50R20 tires btw 36-37 psi verses Factory setting of my Standard 18" Wheels set higher at 40-41 psi?
Gas mileage w/ the Factory 18" Wheels (City driving only - or - All Stop & Go driving) was a terrible 15 mpg. After upgrade to 20" Wheels (City driving only - or - All Stop & Go driving) getting 17 mpg!

 

[snobrdrdan]

I even get better gas mileage by a couple of mpg with the 20" wheels so far at least? May have something to do with setting psi of 20" Wheels 245/50R20 tires btw 36-37 psi verses Factory setting of my Standard 18" Wheels set higher at 40-41 psi?
Gas mileage w/ the Factory 18" Wheels (City driving only - or - All Stop & Go driving) was a terrible 15 mpg. After upgrade to 20" Wheels (City driving only - or - All Stop & Go driving) getting 17 mpg!

Hmmm....if I had to guess, the 20" wheels/tires weigh more than the 18" wheels/tires and that usually results in less MPG's since it takes more gas/momentum to get that extra weight going from a stop.
And city driving will DEFINITELY kill the MPG's regardless.

Did you weigh each combo, for comparison, btw? (the 18" wheel/tire vs the 20" wheel/tire)

My wife's 17" winter setup on her 2022 Traverse weighs more (the Blizzaks are heavy) than the 18" OEM wheel/tire setup and her MPG's are suffering because she has a lead foot from a dead stop....for example

 

[jongri]

I only drove a total of 79 miles on the 18" Wheels before installing the 20" Wheels. The average mpg for those 79 miles on the 18" was just under 15 & trending slightly downward. I reset Average Fuel Economy after switching to 20" & average mpg now between 17-19 & trending slightly upward (same distance, same Stop & Go driving). Never weighed the 18" or the 20" (both feel about same weight w/ mounted tires though). Only difference I know for sure is the 18" 245/60R18's were factory set to 40-41 PSI & 20" 245/50R20's set to 36-37 PSI. But with only 79 total miles on the 18" I'll never really know unless I switch them back & compare both with at least 1,000 miles for a more realistic comparison but highly unlikely I'll be motivated enough to do it, lol. I'm not stating 20" get better mpg than 18" by any stretch. Perhaps the Factory set PSI of 40-41 on the 18" Rims is why mpg was lower? Had I adjusted the 18" to 36-37 PSI my mpg might have been higher?
You nailed it on the city driving killing mpg for sure especially w/ AWD!

 

[peterweb]

I only drove a total of 79 miles on the 18" Wheels before installing the 20" Wheels. The average mpg for those 79 miles on the 18" was just under 15 & trending slightly downward. I reset Average Fuel Economy after switching to 20" & average mpg now between 17-19 & trending slightly upward (same distance, same Stop & Go driving). Never weighed the 18" or the 20" (both feel about same weight w/ mounted tires though). Only difference I know for sure is the 18" 245/60R18's were factory set to 40-41 PSI & 20" 245/50R20's set to 36-37 PSI. But with only 79 total miles on the 18" I'll never really know unless I switch them back & compare both with at least 1,000 miles for a more realistic comparison but highly unlikely I'll be motivated enough to do it, lol. I'm not stating 20" get better mpg than 18" by any stretch. Perhaps the Factory set PSI of 40-41 on the 18" Rims is why mpg was lower? Had I adjusted the 18" to 36-37 PSI my mpg might have been higher?
You nailed it on the city driving killing mpg for sure especially w/ AWD!

Did you also reset the MPG when you first picked up the vehicle to drive those 79 miles? If not, the time idling from the factory floor to any testing and to storage is going to be included in your 15 MPG average figure.

 

[jongri]

Did you also reset the MPG when you first picked up the vehicle to drive those 79 miles? If not, the time idling from the factory floor to any testing and to storage is going to be included in your 15 MPG average figure.

Great point and thanks for your question peterweb, much appreciated. My new Pacifica had 36 miles when I purchased it (not included in my 79 miles) and Dealer took the time to show me how to operate everything in detail (Instrument Panel, Uconnect 5 Nav, paired my iPhone & iPad, Sunroof, Stow & Go Seats, etc.) including resetting the Average Fuel Economy before I left Dealership. However with only 79 total miles (not including first 36 vehicle miles) I doubt that's enough to safely state lower mpg experienced with standard 18" Wheels was caused by factory set 40-41 PSI or even enough mileage to conclude anything comparing 18" verses 20" Wheels mpg? I stated my initial observation of 20" Wheels getting 2 MPG higher w/ PSI set to 36-37, but don't believe it would hold up as fact by any stretch of imagination,lol.