Rohana RC10 20x9 20x10
06-29-2012, 06:51 PM
#28
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05 E55
Salty-I have read a million places that on the average size automobile wheel, 1 lbs of rotational mass is equal to about 4 lbs of static weight.
Your stock 18 inch wheels are 26 lbs approx. Your aftermarkets are 30lbs.
By this theory, if the wheels were the SAME SIZE: Each wheel is 4 lbs.x 4 wheels=16 lbs roatational mass. Multiply that by about 4 to equal the drag of about 64lbs. of static weight.
Now your 30 lbs aftermarket wheels are 20 inches in diameter, putting the meat of the wheel (the barrel) another inch away from the rotational axis. This again adds drag. The further away from the axis the weight is, the more rotational inertia you experience. (In my best layman's physics analysis) You may not notice this on the street (I def have in my vehicles, which is why I would never have 20's on my E55) but with the same car at the same track under same conditions with smaller lighter wheels vs heavier larger diam wheels you will def see a difference in ET and trap.
Fortunately it's your ride and if you like the 20's and your ride quality suits you-Rock on brother. That's what it's all about.
Edit: I just noticed Cj's informative response right after posting this. Good info.
Your stock 18 inch wheels are 26 lbs approx. Your aftermarkets are 30lbs.
By this theory, if the wheels were the SAME SIZE: Each wheel is 4 lbs.x 4 wheels=16 lbs roatational mass. Multiply that by about 4 to equal the drag of about 64lbs. of static weight.
Now your 30 lbs aftermarket wheels are 20 inches in diameter, putting the meat of the wheel (the barrel) another inch away from the rotational axis. This again adds drag. The further away from the axis the weight is, the more rotational inertia you experience. (In my best layman's physics analysis) You may not notice this on the street (I def have in my vehicles, which is why I would never have 20's on my E55) but with the same car at the same track under same conditions with smaller lighter wheels vs heavier larger diam wheels you will def see a difference in ET and trap.
Fortunately it's your ride and if you like the 20's and your ride quality suits you-Rock on brother. That's what it's all about.
Edit: I just noticed Cj's informative response right after posting this. Good info.
Last edited by Helli217; 06-29-2012 at 06:54 PM.
06-29-2012, 10:48 PM
#29
Former Vendor of MBWorld
Good info there. Definitely a choice to be made. Looks vs. performance can be a trade off unless you want to spend the big bucks and do a one piece forged wheel. Many owners who do not intend to track their car or do any type of "speed contests" on the public roadways have no issue installing what would be a heavier wheel to get a certain look. Like you mentioned, a matter of preference.
