EV range and wheel size

I would think the reason is that larger wheels weigh alot more. Not just the net weight added to the vehicle but also the fact that it is adding to the rotating mass of the drivetrain. Aero would also be a factor as would different tire if they change with wheel size.

 

It is due to larger rotational mass and more weight. Larger wheels are slower and less efficient, but handle/look better.

 

I can't imagine the wind resistance or weight of tires would make that much difference... I wonder if it is just the larger tires reflect less miles on the odometer - Same real miles, just less miles reported.

 

No, it is mostly rotational mass (larger wheels have shallower tire walls, so the same diameter). The wheels turn about 800 times in a mile, so the weight and rotational mass make a big difference. It is not the same as adding 40 lbs to the car. It is well documented in ICE cars as well. For example read this article:
https://www.caranddriver.com/features/a15130598/upsized-wheels-tires/

 

I for one would have preferred 17" size wheels for the Clarity - not only would the ride be smoother and less jarring under potholes, but the costs of the tires would be less as well.....

My recently retired Land Rover had 18" wheels on them and they rode well. When I test drove the 19" and 20" wheels, they rode very rough.

Maybe I am getting old ?

 

I think that the Jaguar website is using the weight of their OEM wheels in their calculations. It's well-known that OEM wheels are usually quite heavy compared to some aftermarket options. I remember when I had my Civic, the 15" wheel weighed about 20 lbs with the tire off. My friend had some 17" Joustmeister wheels, weighing in a 13 lbs each and got significantly better MPG than I did, despite having larger wheels. It'd be interesting to weigh a Clarity wheel, then look up the weight of the tire and get the weight of the bare wheel next time I have them off.

 

There's a reason why runners, whether they are sprinters or marathoners, don't wear steel toe work boots instead of lightweight running shoes. Hardcore bicyclists spend crazy amounts of money for the lightest, strongest sets of wheels to gain more speed with less pedal power required.

 

I was doing my tire rotation yesterday and had a chance to weigh the wheel. 53.6 lbs with the tire on (n=2, sd=0). The Michelin Energy Saver A/S in 235/45R18 reportedly weighs 25lbs according to TireRack's spec sheet, which is pretty average for a tire of this size. That means the Clarity OEM wheels are 28.6 lbs (actually probably more, as my tires have 17k miles on them already), which is crushingly heavy and a huge source of inefficiency. I've read that every pound of unsprung weight corresponds to something like 3 lbs of sprung weight, so by switching wheels to something like a set of relatively inexpensive Enkei RPF-1 (17.6lbs for 18x7.5 et48), it'd be like losing >130 lbs of weight from the car. Getting more spendy and getting a set of WedsSport TC105N in 18x8 et42 would not only fit a little more flush and look better, but would also drop down to 16.1lbs per wheel -- the weight savings would be like gutting the entire interior of the car!

 

This is typical for an OEM tire. 28.6 lbs is not bad for an 18 inch OEM tire with aero blades. The Enkei and WedsSport won't meet the OEM durability specs, unless Honda uses prohibitively expensive forged wheels. Using a light weight wheel will improve dynamic behavior and low speed range, but high speed range could suffer due to poor aerodynamics (no aero blades).

 

Enkei is the manufacturer for many OEM wheels across several makes, I wouldn't lump them with junk aftermarket manufacturers like you'd get at Discount Tire or Walmart. While you may not be able to smash them into a curb like an OEM wheel, they'll definitely be safe for regular driving. I think that dropping over 10lbs per wheel will have a larger effect on efficiency than any aerodynamic modification.

 

Picked up a 2019 Clarity Base a couple of weeks ago and was surprised that the OEM wheel setup wasn't lighter. I remember when Honda would make a HX/HF version of the Civic and would put lighter rims on those cars, of course that was 30+ years ago and those cars were much lighter. On my scale, the factory wheels (Enkei) & tires weighed in around 55lbs total (1.1lbs being the hubcap). For comparison the Tesla M3 weighs in around 47lbs. I'm going to try some lighter 19" wheels and see how the car rides, handles, and what happens to range and will report back.

 

Will you put low-rolling resistance (LRR) tires on those 19" wheels? If so, which ones?

 

I ordered the Continental PureContact LS in 235/40R19, it's listed as a LRR tire. The OEM Michelin's are exceptional low friction tires, for me I'm willing to sacrifice some of that to get a tire that handles better. Of course we all have different driving styles, but for me the stocks squeal quite a bit whenever I'm cornering on freeway off/on-ramps. If everything goes as planned, my 19" set should be 7-9lbs each lighter than the OEM set-up.

 

Those lighter wheels should make the Clarity PHEV's great ride feel even better!

 

I say go BIG or go home!