can someone ELI5 why the range is worse with larger diameter rims? Is it just higher rotational inertia?
The larger wheels have larger contact patches. The 20" wheels on Continentals use a 265/45-20 front tire and 275/45/20 rear tire. The tread width on those tires end up being 8.5" in the front and 8.9" in the rear. Compared to the 22" wheels w/ Pirelli Scorpions, they use a 265/35-22 front tire and a 285/35-22 rear tire. Those give a 9.5" tread width in the front and 10.5" in the rear. What does that mean? That means more tire is touching the ground, which creates more friction. Similiar to how towing a trailer creates air friction, this would be creating ground friction.
If we took a look at the tread width comparisons, it would be 11.7% larger on the 22" wheels and 17.9% larger on the rear tire. Taking all 4 into account, it comes out to be roughly 14.9% larger tread width for the contact patch which looks like a pretty familiar number. There's more that goes into it like load and PSI; but simplified the additional traction/friction from the 22's account for a lot of the efficiency loss.
If you have the Goodyear Eagle F1s instead of the Pirelli Scorpion Zero's, the mileage issue is slightly worse. The contact patches on the Goodyear's are 15% larger front, 18% larger rear. The traction ratings are also AA rated vs the A of the Pirelli's with a much higher rate of wear. This would indicate that as a tire, it's a stickier tire. That's good for traction, but bad for efficiency.
The second part of it is weight. In addition to being unsprung weight, the wheels and tires are a rotating mass. All of this means that a single pound of weight on those components is equielant to several multiples of that weight if it were inside the cabin.
For comparison again, weights for each not including air or wheel weights for balancing. 20" wheels on Continentals weigh in at 30lbs per tire for a wheel/tire combo weight of 62lbs front, 63.2lbs rear. The 22" wheels on Pirelli's are 71.6lbs front, 78.4lbs rear. That's 15.5% higher in the front, and 24% higher in the rear. Overall that's 19.8% more weight. Again, another number that looks familiar.
So what do you do if you absolutely want the oem 22's and don't want to take as bad of a mileage penalty? Look into other tires and overinflate a little. The Continental Extremecontact DWS 06 tire as an example weighs in at 27lbs on the front, 3 lbs lighter than the 20" oem tires and has a tread width that is just 7% larger.
Mainly because of how the weight is further from the center. I find however that the arachnid wheels in my s have improved my range , maybe even close to what people get on slip Streams, they are very light.... would be interesting to get some narrow carbon fiber wheels .... would add like 800 miles of range
I got curious about your arachnids, so I ran those too. I know the arachnids are forged and lighter, which probably offsets the traction penalty. On a 19" slipstream wheel with the Michelin Primacy MXM4 tire, it has a total weight of 57lbs per corner with a tread width of 8.4" Compared to the 21" arachnids, which weigh 52.85lbs on the front and 55.75lbs in the rear. On all 4 corners, the arachnids are 10.8lbs lighter than the slipstreams for a 5.1% weight reduction; even more if you're running a boxed setup.
When we get into looking at tread width, the slipstreams have a 8.4" contact patch using a 16" Michelin Primacy MXM4. It goes to 9.1" front and 9.5" rear on the 21" on Michellin PSS tires. On all 4 corners, that's 10.7% larger. Interestingly, if you went with the Contisport Contacts, the front treadwidth is exactly the same as the 19's and only the rears being larger. This setup would end up being only 4.2% larger on all 4 corners.
What's your exact setup? It might end up implying unsprung weight is the major factor here.
