Based on my experience with Kyowa 17" rims with 205 mm width tires did take a few MPG hit on the highway. I think it is the combination of non-LRR tire, wider width, aerodynamics of the spokes and the offset of the wheel. The aftermarket rims have the offset (mine was 42mm) that pushes the wheel out (to corner better). I believe that affects the turbulence optimization near the wheel wells.
Here you go all the information on the sp10 MOTEGI RACING SP10 Hyper Black 40 mm offset. I don't think the tires effected my mileage much as rolling resistance is fairly constant mpg with velocity until you go too fast and the tires start to heat up. The aerodynamics of the rims could have definitely changed the fuel economy as drag is the dominant loss at 86 mph cruise control. I don't have a wind tunnel anymore so your guess is as good as mine on how much extra drag the rims caused.
For what it's worth, since I'm no engineer or physicist and know only the basic stuff about aerodynamics, I noticed the drag from the wheels plays a small role in mileage. Especially with your more informative post regarding how speed affects aerodynamics I would assume that the faster you go, the worse it gets. For instance I pulled off the plastic rims from my Prius and noticed immediately with the same commute everyday and the same driving style I was scoring at least 2-3 mpg less than before, and I drive 55 mph on the freeway. Popping the covers back on earned me those back. Again no scientific experimenting, no peer reviews haha, just a layman's observations.
I agree. All of my 17" tires always created a hit on highway mpg as well as city. It is a sustained drop no matter the speed. I feel it is complete bogus when someone says that their highway mpg was not affected by the upsizing of tires on our cars. Apples to apples you will always suffer a loss at high and low speed. I tried to keep the offset as close to OE as possible at 45mm and I used the best LRR tire we know of in the 17" size and I still see a hit at freeway speeds where wheel/tire weight is not supposed to have much of an effect.
I read someone saying rolling resistance is fixed regardless of speed. Wouldn't the increased air rushing over the car push the vehicle down the faster you go thereby, in effect, increase the weight of the vehicle, which would in turn increase the rolling resistance?
I certainly did not say that. I answered with both my wheel and tire specifications. At low speeds the tire matters. At high speeds the aero dynamics of the new wheel matters. At 40 mph you are giong to feel mainly the rolling resistance effect, at 85 mph mainly the drag. Wheel weight won't have much effect at freeway speeds if you stay in cruize control. It takes more energy to get to speed, but you can use it when you slow down. Think of the weight in a flywheel. The term is Frr x v = power, but since we are talking about energy over distance the speed of the car is cancelled out by time/distance. When you are accelerating or decelerating there are changes, but even at 85mph in unaccelerated (cruise control) the rolling resistance is fairly constant. Traction does change with turns and I was on a winding road. I would not use my test for flat straight roads, those should offer significantly better results.
I did, it was very hilly with a winding road. Results are above but Mileage for the loop 32.2 indicated. Going south and uphill was 28.2, coming back was 37.2. We are discussion how much my wheels and tires reduced the mileage. I think its best to keep the car at 80 mph or below if you want good fuel economy. You can safely go 80mph on this 85 mph road, and most were going slower than that.
I was not referring to you in my post. I should have made that more clear so I apologize. My statement was more broad and was directed at the general audience. I agree with your statements above, completely.
Brand new pure stock 2012 Prius III. Driven 200 miles from Los Angeles to San Diego and back. Cruise Control @ 80MPH a good 50 miles of it with 1 passenger. I can say, my meter says 40.3MPG, but It may be between 35-39MPG if driven on 80MPH.
I can tell you first hand that in 10,000 miles I'm getting 42.3 mpg. I drive fast, allways have it's a flaw. I drive 80+ more than 40 miles one way five days a week for work plus trips from Buffalo to NJ and MA now on these trips I don't know where the cops sit like I do on the way back and forth to work so I back it down to 75. That said I started trip B when I bought the car in July of this year, I'm now just over 10K and it reads 42.3mpg, and yes this does include slower in-town driving not all thruway milage. Trip A I set for a short trip (1000 miles) and tried staying at 70 on my Gen II just before I parted with it in July and I got 44 something. BUT it felt like I was crawling This has all been warm/mild weather these numbers and my speed will change when snow starts.
If you read my post, I did the test at lawfull speed of 85mph on speedometer - 86 mph gps, legal on 85 mph posted speed limit in Texas But your post is offensive. You dumb down everything so murders with negative political agendas and speeders are equal in your eyes. Please think of the victims of terrorism before you use that disgusting thinking again.
