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California98Civic · 07-28-2019, 09:00 AM

I wanted taller than stock rims that were also lighter, so I ended up with 15" 2007 BMW MINI seven hole rims (12 lbs). For a cover I blanked the holes from behind to create a "flat" surface preventing airflow THROUGH the rim face. This should prevent almost as much wheel drag as smooth covers while keeping my overall weight to about 12.5 lbs per wheel. Smooth covers would do slightly better but they tend to go onto heavier wheels, to which the cover itself adds weight.

Here is some of the data behind the thought behind blanking lightweight rims:

Here is the look:

CITATIONS:

This is mostly a reposting of post #421 in my own modding thread (see link in sig file below).

"AEROHEAD" opinion cite... somewhere on ecomodder.com I swear it.

Alexey Vdovin, "Investigation of Aerodynamic Resistance of Rotating Wheels on Passenger Cars," (Gothenburg, Sweden: Department of Applied Mechanics, CHALMERS UNIVERSITY OF TECHNOLOGY, 2013).
http://publications.lib.chalmers.se/...302/176302.pdf

See also:
http://publications.lib.chalmers.se/...ext/133661.pdf
"Blocking the crossflow through the rims result in increased static pressure in the front wheel house and thereby an increase in lift, whereas blocking the crossflow in the rear result in increased downforce due to an increased flow rate through the diffuser. It was however shown that the resulting flow around the rear wheel was highly dependent of the rim design in the front."

07-28-2019, 09:00 AM	#12 (permalink)
California98Civic Cyborg ECU Join Date: Mar 2011 Location: Coastal Southern California Posts: 6,299 Black and Green - '98 Honda Civic DX Coupe Team Honda 90 day: 66.42 mpg (US) Black and Red - '00 Nashbar Custom built eBike 90 day: 3671.43 mpg (US) Thanks: 2,373 Thanked 2,172 Times in 1,469 Posts	I wanted taller than stock rims that were also lighter, so I ended up with 15" 2007 BMW MINI seven hole rims (12 lbs). For a cover I blanked the holes from behind to create a "flat" surface preventing airflow THROUGH the rim face. This should prevent almost as much wheel drag as smooth covers while keeping my overall weight to about 12.5 lbs per wheel. Smooth covers would do slightly better but they tend to go onto heavier wheels, to which the cover itself adds weight. Here is some of the data behind the thought behind blanking lightweight rims: Here is the look: CITATIONS: This is mostly a reposting of post #421 in my own modding thread (see link in sig file below). "AEROHEAD" opinion cite... somewhere on ecomodder.com I swear it. Alexey Vdovin, "Investigation of Aerodynamic Resistance of Rotating Wheels on Passenger Cars," (Gothenburg, Sweden: Department of Applied Mechanics, CHALMERS UNIVERSITY OF TECHNOLOGY, 2013). http://publications.lib.chalmers.se/...302/176302.pdf See also: http://publications.lib.chalmers.se/...ext/133661.pdf "Blocking the crossflow through the rims result in increased static pressure in the front wheel house and thereby an increase in lift, whereas blocking the crossflow in the rear result in increased downforce due to an increased flow rate through the diffuser. It was however shown that the resulting flow around the rear wheel was highly dependent of the rim design in the front." __________________ See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.