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.

 

Variables:
route
driving style
ambient temperature
A/C use
Tire inflation/contact patch
wheel mass properties.
slightly varying wheel sizes
Battery capacity (state of degradation)
Battery SoC
# of recals
a 20# variation on a curb weight of 2875#

From my perspective, a 1% variation in the weight of the car is likely the tiniest influencer of mileage.

Of the wheel/tire influence, the polar moment of inertia would likely carry far more influence than the weight itself. The centroid of a larger wheel and lower profile tire is likely farther from wheel centerline than the stock config thus requiring more torque to accelerate the mass of the wheel. But again, this amount of torque is tiny compared to the torque required to accelerate the mass of the vehicle.

Contact patch characteristics would play a more significant role than wheel weight/config as a 10% increase in contact patch would have a comparable increase in rolling friction.

Personally, I experience a substantial fluctuation in economy with no wheel/tire changes. During AZ summer months with A/C use, I'm happy with 36mpg in mixed driving (sometimes as low as 34mpg). During winter months with no A/C use, I'm unhappy with less than 44mpg (sometimes as high as 47mpg).

I realize this isn't what you asked for, but I hope I've illustrated that the change of the weight of the wheel is likely the least of your concerns. Personally, if I got fancy new wheels, I can guarantee you my mileage would drop because I would drive more "enthusiastically."

I encourage you to pursue your current plan of experimentation. I would suggest that you use the "B" trip meter with purpose. If you want to assess mileage under normal use, track your mileage for five round trips to/from work. Insure proper inflation. Reset "B" each day and note car-reported temp at destination (arrive at work, arrive at home), distance traveled, AC use, subjective assessment of driving style (mild, normal, aggressive), battery SoC and occurrence of recals. Confirm overall mileage for the week by filling up and computing mpg.

Rinse and repeat two more times and compare the reults. The biggest issue will be the ambient temp over the 2-3 weeks. As temps cool off, your thermodynamic efficiency will improve, and your mileage may measurably improve regardless of wheels installed.

Good luck!

Steve

 

Your car couldn't care less about what the tires weigh. The key is to use a tire that is tall and narrow. Along with that inflate them about 4 pounds over the Honda suggested inflation rate so they will roll better. Tread pattern also has a LOT to do with this.

So back up and punt. If your previous setup worked better don't change it.

 

the larger wheel and tire probably has a lot to do with it, requiring more torque to spin, also the stock wheel was designed to be aerodynamic to help save on gas. or maybe the larger wheel and tire is effecting your odometer reading, and skewing your numbers

I'll try to find video, but there was a test done on an rsx that was being built to race, they got a bigger wheel and tire, but was lighter than the stock rims. On comparing the dyno pulls, they lost power due to the wheel and tire.

if you want different wheels and tires, maybe switch back to a stock wheel and tire and you may get some mpg back.