Go Back   EcoModder Forum > EcoModding > EcoModding Central
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 07-18-2009, 12:32 PM   #1 (permalink)
Minimal to the maximum
 
bucknmusky's Avatar
 
Join Date: Jan 2009
Location: Appleton, WI
Posts: 12

Enola Gay 2.0 - '02 Chevrolet Cavalier Base coupe
90 day: 40.44 mpg (US)

White-tail Hearse - '02 Chevrolet Silverado 1500 LT extended cab
90 day: 15.3 mpg (US)
Thanks: 0
Thanked 0 Times in 0 Posts
Wheel (rim) size and performance

I currently drive a 2002 chevrolet cavalier with the stock 14" steel rims and plastic 5 spole wheel covers. I was looking into getting the moon disc hubcaps to cut down on drag. I have access to a set of 15" factory steel wheels, from another cavalier and so was wondering if the larger rims (with the 15" moon disc hubcaps) would do more good becasue the tires are the same overall diameter so more of the outer area of the tire/wheel combo is actually covered by smooth metal and there would be less deflection because of smaller sidewalls, or would larger rims add additinal rotating mass where is should not be and negate any areodynamic advantage. Too expensive for A-B-A testing for me so I will take opinions as a good second opinion. thanks y'all

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 07-18-2009, 04:58 PM   #2 (permalink)
OCD Master EcoModder
 
brucepick's Avatar
 
Join Date: Dec 2007
Location: Eastern CT, USA
Posts: 1,918

Outasight - '00 Honda Insight
Team Honda
Gen-1 Insights
90 day: 59.79 mpg (US)
Thanks: 405
Thanked 371 Times in 250 Posts
I think you're right in that there might be a slight advantage in a slightly larger moon hub cap on a wheel/tire combination with same final outer diameter. However don't think the extra inch diameter would make that much difference.

You should weigh the two wheel/tire combinations and see if one is heavier. Tires are rotating mass and depending on who you read/believe, any additional mass will work against you 2x to 3x as much as if it were non-rotating mass. That's especially true for any driving where speed varies. Go with the setup that weighs less.

The "rotating mass" reduction thing is what originally drove performance enthusiasts to mag wheels and alloy wheels. Has nothing to do with bling - that came much later.

You can look up the weight of current available tires at tirerack.com if you need to. It's under "specs" for most tire make/models.
__________________
Coast long and prosper.
Driving '00 Honda Insight, acquired Feb 2016.


  Reply With Quote
Old 07-18-2009, 07:49 PM   #3 (permalink)
Master EcoModder
 
Join Date: Jun 2008
Location: Earth
Posts: 5,209
Thanks: 225
Thanked 808 Times in 592 Posts
Quote:
Originally Posted by brucepick View Post
You should weigh the two wheel/tire combinations and see if one is heavier.
Just weighing won't give an accurate answer: what matters is the rotational inertia, which is mass * distance from axis. So if you had two wheel/tire sets that weighed the same, one with a heavy tire & light wheel, and one with a light tire & heavy wheel, the heavy wheel set would have less inertia.

I've wondered about this sometimes: would a big rim & skinny tire be more efficient?
  Reply With Quote
Old 07-20-2009, 07:42 AM   #4 (permalink)
Master EcoModder
 
blueflame's Avatar
 
Join Date: Nov 2008
Location: Auckland NZ
Posts: 333
Thanks: 7
Thanked 13 Times in 10 Posts
Larger diameter equals higher ratios equals better FE if loading is okay. Weight/inertia characteristics arnt too important at constant speeds
  Reply With Quote
Old 07-20-2009, 12:18 PM   #5 (permalink)
Master EcoModder
 
Join Date: Jun 2008
Location: Earth
Posts: 5,209
Thanks: 225
Thanked 808 Times in 592 Posts
But the question was which is better, assuming the same overall diameter...
  Reply With Quote
Old 07-20-2009, 05:36 PM   #6 (permalink)
Master EcoModder
 
chuckm's Avatar
 
Join Date: Aug 2008
Location: Monroe, LA
Posts: 308

Exploder - '02 Ford Explorer xlt

Rolla - '02 Toyota Corolla ce
Team Toyota
90 day: 44.43 mpg (US)
Thanks: 11
Thanked 13 Times in 12 Posts
More weight distributed to the outside would increase rotational inertia, meaning it take more energy to accelerate. If the trade is between heavy tire on a light rim or a light tire on a heavy rim, go with the light tire on the heavy rim (assuming total weight is approximately the same).

__________________
"Jesus didn't bring 'Natty Lite' to the party. He brought the good stuff."
  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
What effect from tire size and type? PonchoBuick EcoModding Central 1 11-17-2008 04:03 PM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com