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light weight wheels, does it matter ????

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Discussion starter · #102 ·
team3d said:
LINK: http://forums.nasioc.com/forums/showthread.php?t=2027575


I been wanting to find out for myself if the weight of wheels and tires would have an effect on the power and on the performance of the car at the track. I finally had the chance to do the test, and to confirm with my own eyes that indeed the weight of wheels and tires can affect the car's power. Here is the test that I conducted, and the results:

TEST
To see the effects in power by only changing the wheels and tires of a car on the same day.

WHEELS AND TIRES
Heavy Wheels and Tires
18x9.5
245/40/18

Light Wheels and Tires
17x7
215/45/17

PROCEDURE
With the heavy wheels already on the car, I checked and adjusted the pressure on the wheels to 35 psi. Then drove to my test track and did 3 back to back pulls, starting at 2000 RPM to about 6500 RPM. I make sure to start the pull at the same place on the test track, the starting point is marked by a speed limit
Image
.

After doing the pulls, I went back home and took the wheel off the car and weighted each of wheels and tires on a digital bathroom scale. Then adjusted the pressure on the new lighter wheels to 35 psi and weight them on the bathroom scale. After recording all the weights of the wheels and tires, I installed the new wheels on the car and continued by doing the 3 pull just as stated above.

Results
Heavy Wheels and Tires
Individual Weight: 46.4 lbs, 46 lbs, 46.4 lbs, 46.6 lbs
Total Weight: 183.6 lbs

Light Wheels and Tires
Individual Weight: 36.2 lbs, 35.8 lbs, 36.4 lbs, 37 lbs
Total Weight: 145.4 lbs
Difference in Weight= 38.2 lbs

Pulls With the Heavy Wheels and Tires
Time: 9:25 am
Ambient Temp: 88 degrees Fahrenheit
Road dyno #s:
Pull 1= 283whp/ 319wtq
Pull 2= 279whp/ 318wtq
Pull 3= 283whp/ 308wtq

Pulls With the Light Wheels and Tires
Time: 3:18 pm
Ambient Temp: 101 degrees Fahrenheit
Road dyno #s:
Pull 1= 307whp/ 338wtq
Pull 2= 305whp/ 338wtq
Pull 3= 307whp/ 338wtq
Image


Image
Click to expand...


this test, the op shaved a total of 40lbs off the wheels & tires was able to gain +22whp (average), but for 2wd, the gain will be much less substantial
 
#104 ·
Discussion starter · #105 ·
Jtesterman14 said:
team3d said:
this is light weight !

http://www.9thgencivic.com/forum/attachments/wheels



Is that your wheel/tire?[/QUOTE]

no, it's PJ's, his driving up from san diego to pick them up next week.

[QUOTE="kev604, post: 3321650, member: 8775"]Need to provide specs on wheels and tire to put those numbers into perspective and if your really anal need to provide what PSI those tires are running at to get the entire picture.[/QUOTE]

for bolt-on's we use oem size, 25" tall, 225-45-17 tires and the width don't matter too much, between 17x7~17x9, and we all use oem recommend tire pressure.


as for pj's advan racing RGD, he shaved a total of 52lbs for the complete set up (compare to stock)
Click to expand...
Click to expand...
 
#109 ·
Really good data here. I had a set of BBS Forged wheels (stock Evo 9 SE wheels) lying around from my 2006 Evo 9 and popped them onto my car. I was blown away by just how heavy the stock 18" wheels were. I was able to go from a 215/18 to a 235/17, which means slightly cheaper tires, more contact patch, and a much lighter wheel and tire setup. I experienced the same result as many have here, better throttle response and improved in gear acceleration.
 
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#110 ·
Been away from this board for a while but I LOVE this stuff. Thanks team3d for providing that link. It's good reading (Just finished reading it). I've seen other magazine articles like in the past. I've done this same thing on my Fit, RAV4 and both my Subarus. Low weight wheels, reduced the diameter from stock if I could, low weight 'good performing' tires and reduced the diameter of the tires slightly (Not recommended). The reduced diameter is just a preference of mine as I know (like the article indicates) it has even more of an effect than the lighter wheels. The lighter tires have more of an effect than the lighter wheel because the weight being reduced is further away from the center of force (axles turning the wheel).

People still wonder why I run the numbers I do with simple mods. Good stuff! 3 thumbs up!
 
#111 · (Edited)
team3d said:
LINK: http://forums.nasioc.com/forums/showthread.php?t=2027575


I been wanting to find out for myself if the weight of wheels and tires would have an effect on the power and on the performance of the car at the track. I finally had the chance to do the test, and to confirm with my own eyes that indeed the weight of wheels and tires can affect the car's power. Here is the test that I conducted, and the results:

TEST
To see the effects in power by only changing the wheels and tires of a car on the same day.

WHEELS AND TIRES
Heavy Wheels and Tires
18x9.5
245/40/18

Light Wheels and Tires
17x7
215/45/17

PROCEDURE
With the heavy wheels already on the car, I checked and adjusted the pressure on the wheels to 35 psi. Then drove to my test track and did 3 back to back pulls, starting at 2000 RPM to about 6500 RPM. I make sure to start the pull at the same place on the test track, the starting point is marked by a speed limit
Image
.

After doing the pulls, I went back home and took the wheel off the car and weighted each of wheels and tires on a digital bathroom scale. Then adjusted the pressure on the new lighter wheels to 35 psi and weight them on the bathroom scale. After recording all the weights of the wheels and tires, I installed the new wheels on the car and continued by doing the 3 pull just as stated above.

Results
Heavy Wheels and Tires
Individual Weight: 46.4 lbs, 46 lbs, 46.4 lbs, 46.6 lbs
Total Weight: 183.6 lbs

Light Wheels and Tires
Individual Weight: 36.2 lbs, 35.8 lbs, 36.4 lbs, 37 lbs
Total Weight: 145.4 lbs
Difference in Weight= 38.2 lbs

Pulls With the Heavy Wheels and Tires
Time: 9:25 am
Ambient Temp: 88 degrees Fahrenheit
Road dyno #s:
Pull 1= 283whp/ 319wtq
Pull 2= 279whp/ 318wtq
Pull 3= 283whp/ 308wtq

Pulls With the Light Wheels and Tires
Time: 3:18 pm
Ambient Temp: 101 degrees Fahrenheit
Road dyno #s:
Pull 1= 307whp/ 338wtq
Pull 2= 305whp/ 338wtq
Pull 3= 307whp/ 338wtq
Click to expand...

Something interesting I saw when playing with the numbers.
The first set of wheels were 245/40-18. The 2nd set was 215/45-17. I plugged these numbers in at Miata Tire Calculator. It comes up with a -4.3% difference. I then multiplied this number times two and got -8.6% difference (Can't remember why I did this. I'm horrible with math).
I then multiplied -8.6% time the whp (283whp X .086) and came up with 24.338whp. I was thinking that this horsepower difference should be the difference between the old wheels and the new ones only based on wheel size.
When you add 24.338whp to 283whp (24.338 + 283whp) the new number is 307.338whp. Our new number.

I am taking this same approach on the 10th Gen civic I have now.
Stock wheels are 215/50-17. My new wheels are 225/50-15. That is a -6.3% difference. -6.3% X 2 = -12.6%.
My stock hp is 174hp. 174hp X 12.6% (174 X .126) is equal to 21.924hp. So I add 21.924hp to 174hp (174 + 21.924hp) is equal too 195.924hp. I'm expecting my wheels to bring me right up to par with the new Si in terms of horsepower. Old wheel weight is about 50lbs. New wheel weight tis 36.6lbs. A weight reduction of 13.4lbs per wheel. This not counting the rotors I'm getting which I expect to be a little lighter as well.

This is my bullshi* math but I just like to do this to justify my purchase. Carry on! :wigglesmiley:
 
Discussion starter · #112 ·
Myx said:
Something interesting I saw when playing with the numbers.
The first set of wheels were 245/40-18. The 2nd set was 215/45-17. I plugged these numbers in at Miata Tire Calculator. It comes up with a -4.3% difference. I then multiplied this number times two and got -8.6% difference (Can't remember why I did this. I'm horrible with math).
I then multiplied -8.6% time the whp (283whp X .086) and came up with 24.338whp. I was thinking that this horsepower difference should be the difference between the old wheels and the new ones only based on wheel size.
When you add 24.338whp to 283whp (24.338 + 283whp) the new number is 307.338whp. Our new number.

I am taking this same approach on the 10th Gen civic I have now.
Stock wheels are 215/50-17. My new wheels are 225/50-15. That is a -6.3% difference. -6.3% X 2 = -12.6%.
My stock hp is 174hp. 174hp X 12.6% (174 X .126) is equal to 21.924hp. So I add 21.924hp to 174hp (174 + 21.924hp) is equal too 195.924hp. I'm expecting my wheels to bring me right up to par with the new Si in terms of horsepower. Old wheel weight is about 50lbs. New wheel weight tis 36.6lbs. A weight reduction of 13.4lbs per wheel. This not counting the rotors I'm getting which I expect to be a little lighter as well.

This is my bullshi* math but I just like to do this to justify my purchase. Carry on! :wigglesmiley:
Click to expand...
dba australia have a math about, rotational weight, for every 10% weight you drop, you use 15% less energy to move to spin the wheels/rotors

but this do not factor friction into account....

link: https://www.dba.com.au/brake-discs-is-lighter-better-2/
 
#113 ·
team3d said:
dba australia have a math about, rotational weight, for every 10% weight you drop, you use 15% less energy to move to spin the wheels/rotors

but this do not factor friction into account....

link: https://www.dba.com.au/brake-discs-is-lighter-better-2/
Click to expand...
Excellent information and link! I just started reading it and the Misses started bugging me about something. Love things like this though. I appreciate the info Team3d. This always useful.
 
#115 ·
As just mentioned in another thread, 15-inch Civic steelies are 18 lbs each.
 
#117 ·
I was on the Enkei website window shopping wheels and Enkei saids that one 1lb unsprung weight is equivalent to 20lbs off the car. Might be a little optimistic number coming from a wheel manufacturer so take that for what it's worth.

The biggest drop in unsprung weight for me was when I changed out the OEM wheels on my wife's car to RPF1 and dropped more than 10lbs unsprung weight per corner. Felt like a different car from a dig, from a roll, cornering and braking. Based on Enkei's calculations dropping 40lbs unsprung weight is equivalent to 800lbs off the car not sure if it was that huge a difference though lol.
 
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