Messed up wheel choice. How bad? Has Anybody compared?

[morkys]

Has anybody compared an open spoke designed alloy wheel with an flatter aero wheel or wheel-cover? How did you find the difference in wheels affected your fuel-economy?

I am a Corolla owner caught between two worlds. I own a 2001 Toyota Corolla CE and like the fact that I get very good fuel economy most of the time, but, can move a little quicker when needed.

Last year, I bought wider 'low' profile tires when my original 175/65R 14 tires died at 100,000 KM. Although wider & slightly taller 195/60R 14 tires, they are H-rated and reasonabley light compared to similar or higher performance tires. With a few extra PSI over stock, I get effectively the same fuel economy or better. In winter I have 175/65R 14 winter tires & with a few extra PSI, they are ok for fuel economy & better grip in snow/ice.

This week, as spring is arriving, I took off the steel winter wheels and tires and bought a new set of 14" Sport Edition D5 alloy rims to mount the 195/60R 14 H-rated all-season tires. Even with bigger tires, the alloy rims and tires are at least a full LBS lighter than the smaller winter tires on steel wheels, because the tires are not much heaiver than the winter tire and the rims are lighter.

I started looking for wheels last year and I remember thinking that the spoke design could potentially be a negative for fuel economy, but I didn't think it too big of a concern. Most of my interest in the alloy wheels were the reduction in weight. Perhaps there was a light-weight 14" alloy rim out there that was more aero. I will track my fuel economy and see what the score is. Other mods I am planning for this car are a freer flowing air intake, freer flowing exhaust including header, lowering the car < 1.3".

Anyhow, if you have had personal experience with wheel designs and fuel-economy, by all means, please let me know your thoughts. If you have a link to something that has measureable data, that's ok too, though I'll be researching that myself too.

[aerohead]

The sticky on seminars and mod data has a section on wheels and some hard science numbers from wind tunnel tests.There won't be data on your particular wheels but maybe from what is there,you can derive some sense of your margins of performance.

[cfg83]

morkys -

Here's one (blurry) reference :



However, this is the conclusion but not the study. I do apologize for not having that hard data reference. I will look for it and post again later.

CarloSW2

[MetroMPG]

Tasdrouille posted an illustrated wind tunnel study of wheel style on drag. It's really good. I'll go see if I can find it now...

No luck so far, but here's the info Phil referred to:

http://ecomodder.com/forum/showthrea...-7-a-2684.html

[cfg83]

morkys -

Here's the explanation of the source of my image :

The VERA-01 is a prototype vehicle developed by Peugeot in 1981. Compared with the production 305's Cd of 0.44, VERA's 0.318 represents an improvement of nearly 30%. Here we use the VERA as an example in which aerodynamic improvements were made using smoke streaks, citing the effectiveness of the measures taken.

Therefore, this is a circa-1981 test done in wind tunnel. Covering the wheels was just one modification that they made.

CarloSW2

[AeroModder]

A note on the freer-flowing intake: On a fuel-injected car, more air coming in means more fuel being used. This will increase power, but lower fuel economy. I've learned this from experience, and my best tank was done with the restrictive stock intake setup.


On the blurry reference: Only one point? Wow. Looks like my stock rims are about as good as I'll get.

[cfg83]

AeroModder -

Originally Posted by AeroModder

...

On the blurry reference: Only one point? Wow. Looks like my stock rims are about as good as I'll get.

Yeah, there's a parked Tempo I pass on the way to work that has ones close to the Treser wheel :



The nice thing about the Tempo was it's "Ford aero-era" design aesthetic.

CarloSW2

[Ecobalt]

I bought aluminum "alloy" wheels that weigh 12.6 pounds each. Per my bathroom scale, my summer tire/wheel combination now weighs five pounds less than my winter tire/stock steel wheel combination. That's gotta be a good thing.

My "OEM" Continental Conticontact tires are designed for quite-low rolling resistance. My Continental Extreme Winter Contact tires have middling rolling resistance. (I knew that when I bought the snow tires). I was getting reduced mileage all winter since installing the "snows", probably 31 mpg. Since I replaced them, my fuel economy has been 33 mpg and 35 mpg on two tankfuls. That is not enough data. My second tankful included a 110 mile road trip where I drove slowly when nobody was behind me.

Konig is a good brand to look for if you want light wheels. Wheel technology is explained at tirerack.com .

[AeroModder]

Unfortunately, all the wheels are identical, so if one direction is sopposed to draw air out of the wheel, the other side draws air in. You can somewhat see them in my avatar.

[morkys]

I'll post some more until I can show a picture of my car. My rims are 14" so that alone means it isn't a large surface area, but....the design I chose may possibly be one which causes poor aero because of the sharp edges. I have Sport Edition D5 14" alloy wheels. The wheels are about 13.2-13.4 LBS using an electronic bathroom scale. The wheels are low pressure cast and shot peened and made by Kosei.

I'm already paranoid that my rolling resistance has dropped since installing the new rims with my wider tires. I have to do a bunch of testing to figure out exactly what the score is. Last year I replaced my 175/65R 14 snow tires with General Evertrek 195/60R 14's and just put them straight onto my stock steel wheels and I swear with similar PSI I didn't notice a change in MPG. This time the rims are lighter, but not as smooth and also 1/2" wider. I think the track is different too, as the offset is different by 7 mm.

thanks for the feedback folks...I guess I'll do some research and start some testing...