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Old 02-17-2003, 02:15 AM   #1
B-Kerr
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Question Anyone with conclusive data on wheel/tire weight effects on 1/8 or 1/4 mile times?

I was just curious if anyone had any data on the effects of tire/wheel combination weight on acceleration, i.e., 1/8 or 1/4 mile times. For all practical purposes, I would prefer 1/8 mile time effects because acceleration and looks is more important on the street; If I want to run good at the track in the 1/4, an ugly set of drag lights and hoosiers would be the way to go.

I'm asking becuase I want to get a good looking set of wheels for daily driving, but 18's seem to weigh so much unless you buy expensive forged wheels. For the few times I would go to the track, I could always revert to stocks. I just thought someone would have a comparison.

Please give some input.

Thanks,

B-Kerr
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Old 02-25-2003, 07:27 PM   #2
psalm
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Don't know about times, but no matter how light your wheel, your 18's will weigh a lot because of the rubber.
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Old 02-25-2003, 11:05 PM   #3
brembo
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A dramatic example would be going from the +/- 50 lb. 17" runflat tire/OE wheel (that's 200 total) to a 15" SSR Competition (8.6 lbs.) with a light tire like a 195/55/15 Toyo T1-S (16.5 lbs.)for a total of 100 lbs.-- that would save 100 pounds off your vehicle weight (roughly like adding 10 extra horsepower) and would have the same effect on A.B.C. vehicle dynmaics as saving a whopping 1,000 pounds of sprung weight.

Hmmm. That seems to good to be true; might have to consult the aforementioned friends to see if those relationships (5:1 wt/hp, 1:10 unsprung/sprung) hold true when one's car goes on a dramatic diet-- I was originally talking about taking only a few pounds off each corner...


From here....

Linkage
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Old 02-25-2003, 11:44 PM   #4
apwrx
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well not totally conclusive but my experience at the track.
best with stock wheel/tires 13.6
best with 18's and 225 13.9
same day same launch etc.
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Old 02-26-2003, 07:36 PM   #5
B-Kerr
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Talking MORE INPUT!!!! Johnny 5 Alive!

AP, just out of curiousity, do you have weights for the 18s w/wo tires? It would be greatly appreciated if you do!

Thanks for the input!

B-Kerr
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Old 02-26-2003, 08:04 PM   #6
Peaty
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I think grass roots did a whole art on that. I have it somewhere.
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Old 03-03-2003, 05:02 PM   #7
kenshiro
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I found this a while back.

http://www.siscom.net/~welter/racing/rotation.html

And here's a list of wheel weights from wheelweights.com.

http://wrx.heavyplasma.com/wheels.pdf
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Old 03-06-2003, 11:10 PM   #8
apwrx
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i forget exaxtly but i am almost pos.its 21lbs without tire
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Old 03-06-2003, 11:57 PM   #9
Kevin Thomas
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B-Kerr,

A really great article for you to read on this would be Sport Compact Car, January 2001 issue (Power, Weight, Grip). They tested 12 wheel/tire combos on 3 cars, on two race tracks and tested 1/4 mile times. Here is one of the test results.

Tire/Wheel info: "Enkei Wheels and BFGoodrich Comp T/A ZRs
225/50-16,
225/45-17,
225/40-18

Enkei 16" RF1 (16's NT03s N/A during test) @44.5lbs wheel/tire weight total

Enkei 17" NT03 @47lbs wheel/tire weight total

Enkei 18" NT03 @46lbs wheel/tire weight total


2000 Mitsubishi Eclipse GT (weight (3050lbs)
Wheel:
16" 15.5@89.4mph
17" 15.5@89.0mph
18" 15.6@87.9mph

Other tests where done as well but this hopefully helps with the 1/4 mile aspect anyway. I figured that most people here would be at or around 3050lbs driving their Impreza. Sorry, no 1/8th info available.

Also, you may be able to somewhat 'offset' the gain in rotational mass of the wheel/tire combo by reducing it somewhere else. For instance, reducing the rotating mass in your flywheel, pulley, pistons, crankshaft, etc. Good luck!
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Old 05-29-2003, 10:26 PM   #10
TripleOne
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My 0-100kmh time was 0.7s worse. Stock was 16" with Advan 205/50, now 18" with Firenza 225/40.
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Old 05-29-2003, 10:41 PM   #11
MJU1983
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my best 1/4 with 18" rota sub zeros with nitto nt555 extremes is 13.064 with a 1.89 60'

best with stockers... 12.64 w/ 1.75 60'

-mike
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Old 05-30-2003, 07:42 PM   #12
B-Kerr
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Default Cool..

Appreciate all the help!

B-Kerr
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Old 05-30-2003, 08:44 PM   #13
makofoto
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look for the current Grassroots Motorsports magazine ... they do a short autoX course test ... the lighter combination was something like a good .1 seconds faster ... maybe a bit more.

I just went from 13 lb. 17 X 7.5 SSR's w/ 225 S-03's at 25 lbs each to 215 Toyo T1S's at 20 lbs each ... and the car feels spunkier ... but don't forget that the T1s's in 215 are also a little shorter ... so that is going to help acceleration ...
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Old 06-01-2003, 02:47 AM   #14
iflybyu
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Default One other thing to consider

.. now I may be wrong on this, but also in cosideration of the weight issue is how far out the weight is. For example, a 15" rim has it's total mass closer to the center - and a 18" rim has it's mass even farther out. I don't remember the physics of it, but it seems to me that the farther the weight is outward of the center, the harder it is to start it spinning - therein loss of power. The reasons for the weight being farther out are somewhat obvious too .. since the rim itself is farther out from the center than a 15" rim - and the tire on a larger rim has all it's mass farther out plus the extra material that's needed to reinforce it's sidewall etc.

I know for instance on my car that the first set of rims I bought (Motegi MR7) made a substantial taxing on the performace of the car. I returned them immediately and ordered Rota Attacks - which had no noticeable difference in performance over stock. The 16" stockers weighed 12lbs a piece lighter than the MR7's w/ 225/45/17 for instance.

Someone may have to correct my physics here..
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