those 255/45R18 = 27" tall tire by 10" wide on the tire size calculator I use.
https://tiresize.com/comparison/
the 2019 traverse 18 X 7.5" wheels are ET50 on the calculator I use.
https://www.wheel-size.com/size/chev...traverse/2019/
just curious if the calculators I have been using are not so accurate?
here is a calculator for wheel offsets that has a visual as well as text description
https://www.wheel-size.com/calc/?whe...96875in&sr=0in
I like more meat on the sidewall for a squishier ride so I will go with the 17's and 235/60's. it's a personal preference thing.