First, I got new Energy Saver A/S installed today. Tire rack, ship to installer. 1 day shipping and I saved $165 vs the lowest local price I was given. I got 73,000 miles out of my oem tires (Goodyear). Now, my question. About a year ago I got some 15" Motegi SP10 wheels. I like their looks, don't love them. I still have the oem wheels and hubcaps. I drive 6000 miles a month so mpg for me is a huge factor. The Motegi wheels are almost 4 lbs lighter per wheel than the stock. But, I assume the stock are more aerodynamic. Which factor is more important? I ended up putting the tires on the Motegi, but almost went back to stock and sold the Motegi. How big of a difference should it make? Second, the inner skirt, aka wheel well on both front wheels is down at least two or three plastic rivets and that plastic skirt is loose, close to rubbing tires. I've never hit a thing in this car so I'm confused as to how these both came loose. Will the fact that they are loose hurt me in the aerodynamics enough to affect mpgs? Before today, with loose wheel well plastic on both front wheels, on the Motegi and Goodyear assurance fuel max, for the 1st 73,000 miles of my 2011, I have always gotten 55-60 mpg at 65 mph, 60+Mpg at 60 mph, 48-51 mpg at 70mph, and 42-45 mpg at 75 mph. I'm hoping the new tires improve those numbers, but can't help but believe I could do better fixing the inner skirts and possibly by having gone back to the stock wheels and hubcaps. Long, I know, I'm sorry. I'm just addicted to getting the best mpg I can. TIA
I'm no expert but if both your original rims and the aftermarket ones are both 15" then I believe that tires mounted on the rim of a lower weight should give better mileage as it takes less energy to spin up that combination to speed. Also I'm not sure how aerodynamic the original steel wheel/covers combination is compared to the aftermarket wheels but I wouldn't think that any difference would overcome the advantage of a lower weight wheel/rim combo.
Just my experience with Prius in the last 7 months of ownership - I have the 17x7 forged rims at about 18lbs; 38.4lbs total with OEM spec Toyo Proxes A20. Can get 52mpg in summer and 50mpg in winter. Perhaps its the tires you were using on the Motegi's?
Only thing I will say is this. The Michelin Energy Saver A/S is the BEST LRR tire out there IMO. Very quiet, GREAT MPG especially if you run them at 42F, 40R. If the ride is too rough drop the air pressure down some but maintain the two pound difference on the front and back. I would think the lighter wheels will benefit you, but can't be certain. I am not a engineer. Just a Prius owner and driver thereof. Ron (dorunron)
Thanks for the replies, I stayed with the lighter wheels because of the same thoughts. The tires are very quiet and very smooth compared to the Goodyears I took off.
Can anyone speak to the drag of the oem wheels? I suppose the .26 (close to) figure for the drag coefficient was prob w the 15s with wheels covers.
