riceball777

I bought my 2006 civic hybrid with the civic ex wheels on the car with stock size 205/55/16 non lrr tires. The seller also gave me the stock 15 inch hybrid wheels with stock size 195/65/15 tires that are also not lrr tires. I have put 15,000miles on my civic hybrid with the stock 16's and I average 40mpg. I have never driven on the stock hybrid 15 inch rims.

I just baught some light weight volks le37k 17x7.5 +40. I bought new 205/50/17 low rolling resistant contenental pure contacts tires. I have put 3,000 miles on this new setup and I'm geting 34-36 mpg. How the hell did I loose 5mpg going to a rim/tire combo that weights 5 pounds less plus I'm now rolling on lrr tires for the first time!!!

The stock 16's with tires weigh 40 pounds and 6oz. The stock hybrid rims and tires weigh 34 pounds and 7oz. My volks with lrr tires weigh 35 pounds and 5oz.

How the hell did I loose 5mpg going from the 16's which weigh 5 pounds more to my 17 inch volks also with lrr tires.

Some one make sense of this for me.

Tonight I just took my volks off and put the stock 15 inch hybrid rims on for the first time ever. Let's see what mph I get with the stock hybrid rims which don't even have lrr tires.

toyomatt84

iTrader: (1)

The only thing I could think of, would be driving style. Maybe, due to the improved grip... you had a slightly heavier foot.

DVDr

iTrader: (2)

It is most likely due to your total wheel diameter/tire combo

stock rims / tire 195/65/15 15 12.675 4.99015748 17.66515748
17 inch 205/50/17 17 10.25 4.035433071 21.03543307


you went from a total of 17.6 inches to 21 inches, this will change your rev range at a certain speed.

so way you always cruised at 50mph , your engine was at X rpm, now with the bigger diameter it will be at a lower rpm ( less torque ? , need more throttle

and it will be harder to accelerate aka get them to move from a stop.

DVDr

iTrader: (2)

weight is not everything in rotating mass.

riceball777

You are wrong. The stock 195/65/15 is a 25 inch diameter tire. I went to a 205/50/17 which is a 25.1 inch diameter tire. The stock 16 inch size is a 205/55/16 which is a 24.9 inch diameter tire. The tire diameter of all the same.

TunerN00b

For acceleration, rotation inertia, not simply weight, plays the role in determining MPG (though I really do think it would be trivial to the point of meaningless).

At speed, the aerodynamics are what determines the wheel & tires combination's affect on MPG. This is why the hybrids come with those ugly wheels. More spokes means more drag. The extreme variant of this is wire wheels, which have horrible aerodynamics and are known to affect mileage.

GagnarTheUnruly

iTrader: (3)

I have a hard time believing a wheel change could effect a 15% increase in fuel consumption, especially if you are still using a low-resistance compound. My guess is some other factor is at work here and it is just a coincidence that you changed wheels around the same time. The only way to know will be to go back to the old wheels and see if your economy improves.

riceball777

Trust me I can't believe it either.

For the first time I'm have been rolling at the stock hybrid 15 inch wheels withe stock size 195/65/15 with cheep non low rolling resistant tires and I millage I can tell is already a huge difference. In the past 2 days with the stock hybrid rims I been getting about 42mpg.

With my new volks with lrr tires. With the volks and tire combo weighing the same if not less than the stock 15 inch hybrid rims. With the volks useing a 205/50/17 which is the same overall diameter as the stock wheels No matter how slow or easy I drive I will never get over 35mpg. Your talking easy 70+ less miles per tank!!!

They say the stock hybrid rims are made to be extremely aerodynamic for the hybrid. I guess this test proves it. I just find it hard to believe that a change in wheel design with out a change in weight or over diameter can affect millage by such a great deal in this car.

GagnarTheUnruly

iTrader: (3)

The wheels give a flywheel effect so I do not think the weight will affect fuel economy one way or the other. I guess it's either the tires or wind resistance on the spokes, or some combination of the two.

kulo

Drive slower

yungmulacrx

How much wider are the 17s?

riceball777

My volks are 17x7.5 stock 16's are 16x6.5. Stock hybrids are 15x6.

Again I have never drove on the stock hybrid rims. I have averaged 40mpg over 15,000 miles on the ex 16 inch rims which are over 5 pounds heavier than my volks. No matter how slow I drive I can only average about 35 mpg with the volks for the past 3,000miles.

I have just been driver on the stock 15inch hybrid rims and have averaged 42-44mpg over the past week. This weigh the same with tires as my 17 inch volks.

Hybrid rims use a 195mm width stock 16's use 205 and my volks use 205. All tire diameter is the same at 25 inches.

Can the aerodynamics of rim design really affect millage this much?

evoM3evo

Wheel change CERTAINLY can/will show dramatic fluctuation in MPG due to the rotating mass, overall weight, tire size, many variables factor in.

TunerN00b

Width significantly affect aerodynamics too.

Wider tires offer lower rolling resistance, but worse aero. Narrow tires offer increased rolling resistance, but improved aero. LRR tires try to combine the benefits of both, by allowing very high pressures to decrease the rolling resistance while running narrow tires, at the cost of traction and safety (braking distance is a safety item).

There's a reason economy cars used to come with 13x4.5 wheels, and it wasn't just initial cost.

So, yeah. Larger diameter wheels, which pushes the weight further out from the center increasing rotational inertia, in increased width providing inferior aerodynamics, could very well affect mileage. How much, I can't say.

P11Gdub

maybe the summer heat is a factor? or maybe the offset differences?

also i like those wheels, are they a variation of the SE37?

riceball777

They are the volk se37k just with a polish lip. Which they call le37k.

P11Gdub

right on, look good.

UA6 BALLER STATUS

Stock wheels are more aerodynamic and have less drag, usually bigger wheels = more rotating mass