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Old 08-25-2005, 12:01 AM   #1
txl146
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Default 1/4 mile time with stock rims vs. heavier rims

I have replaced my summer/track setup with OEM rim/tire. What kind of improvement in 1/4 mile would I expect with lighter setup? My best time with heavier set up was 13.79@97.25mph with 1.90 60' time.

My car feels noticeably lighter with OEM set up as there are about 40 lbs difference between the two (unsprung weight). If same 60' time is achieved, how much of an improvement in either time or trap speed is expected? Once car is in motion, is weight of rim/tire as crucial?

Thanks in advance,
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Old 08-25-2005, 01:05 AM   #2
bren wrx
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some people have reported no difference between 18 and stock, actually same time, i think the difference between 17 and stock would be hard to tell.
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Old 08-25-2005, 01:14 AM   #3
SpoolinU
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I would say negligible......maybe 13.4 around the same speed in theory due to losing 40lbs off the car.
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Old 08-25-2005, 01:23 AM   #4
..:bigFAT:..
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how do you get .39 sec difference with saving only 40lbs from the rims? come on its all in your head
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Old 08-25-2005, 02:59 AM   #5
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Quote:
Originally Posted by txl146
I have replaced my summer/track setup with OEM rim/tire. What kind of improvement in 1/4 mile would I expect with lighter setup? My best time with heavier set up was 13.79@97.25mph with 1.90 60' time.

My car feels noticeably lighter with OEM set up as there are about 40 lbs difference between the two (unsprung weight). If same 60' time is achieved, how much of an improvement in either time or trap speed is expected? Once car is in motion, is weight of rim/tire as crucial?

Thanks in advance,

I believe different offsets of wheels can affect how the car feels and reacts as well.

On FWD cars with very low torque, wheel weights and diameter play a much bigger role from my experience.
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Old 08-25-2005, 04:29 AM   #6
Skully
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You have to look at how the weight is distributed on the stock rims/tires vs. aftermarkets. Even tho the new rims are bigger *weigh less* and there is less tire. More of the mass is moved outwards. Now, with stock rims/tires, the wheel/tire combo is heavier, but the weight more compact and is easier to be turned by the driveline components.

If anyone has anymore input or theories or want to add to what i said, please do. If im wrong. tell me.

-Thomas
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Old 08-25-2005, 08:12 AM   #7
txl146
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Stock setup is lighter.

Stocker with RE92 << P1 and RE070

Last edited by txl146; 08-25-2005 at 08:23 AM.
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Old 08-25-2005, 09:49 AM   #8
OzGC8
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would say 13.5 @ 99/100mph

with same 60' ,shift points and traction

that is my experience out of 170passes and 3 sets of rims

which ones my car wears & loves the most???
Volks TE37 9 lbs per corner(15")
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Old 08-25-2005, 04:49 PM   #9
txl146
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WOW... I guess I will leave my OEM set up on and see how well my car does at the track.
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Old 08-25-2005, 08:42 PM   #10
Kevin Thomas
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Quote:
Originally Posted by ..:bigFAT:..
how do you get .39 sec difference with saving only 40lbs from the rims? come on its all in your head
Sport Compact Car article (Power, Grip, Weight) Januarry 2001 issue.

Car: 2000 Mitsubishi Eclipse GT
Wheels: All Enkei with BFGoodrich Comp T/A ZRs
Sizes:
225/50-16
225/45-17
225/40-18

Weights:
16" = 44.5lbs
17" = 47lbs
18" = 46lbs

Times:
16" = 15.5 at 89.4mph
17" = 15.5 at 89.0mph
18" = 15.6 at 87.9mph

A difference in size and only 3lbs per wheel can net a same time with 1.5mph of a difference in the 1/4 mile trap speed by a professional driver (Rhys Millen). This is with a 3lbs difference in wheel weight (total of 12lbs all 4 wheels). I'm sure a larger difference can be found with a larger weight difference in the wheels.
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Old 08-25-2005, 08:59 PM   #11
turbokonejo
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Stock car rims/tires Sept 2002 14.5@94mph dont remember the rest.
TurboXS Tbe/intake/sti topmount July 2005 16 inch rota slips/snowtires 14.6@93mph
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Old 08-25-2005, 10:12 PM   #12
txl146
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Default

since 1.5 lbs resulted in 1.5mph of a difference, I would expect higher mph gain with 10 lbs of difference....

P1 in 17" = 20lbs
RE070 = 27lbs
Total = 47lbs

OEM rims = 16lbs
RE92 = 21lbs
Total = 37lbs
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Old 08-26-2005, 11:37 AM   #13
SpoolinU
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Quote:
Originally Posted by ..:bigFAT:..
how do you get .39 sec difference with saving only 40lbs from the rims? come on its all in your head
Your right...I must have had a brain fart....should have been .039 off not .39 oops....ah well...pt was maybe he will be a tenth quicker cause shaving 40lbs of rotational mass is better then 40lbs of dead weight.
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Old 08-26-2005, 03:23 PM   #14
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Quote:
Originally Posted by Kevin Thomas
Sport Compact Car article (Power, Grip, Weight) Januarry 2001 issue.

Car: 2000 Mitsubishi Eclipse GT
Wheels: All Enkei with BFGoodrich Comp T/A ZRs
Sizes:
225/50-16
225/45-17
225/40-18

Weights:
16" = 44.5lbs
17" = 47lbs
18" = 46lbs

Times:
16" = 15.5 at 89.4mph
17" = 15.5 at 89.0mph
18" = 15.6 at 87.9mph

A difference in size and only 3lbs per wheel can net a same time with 1.5mph of a difference in the 1/4 mile trap speed by a professional driver (Rhys Millen). This is with a 3lbs difference in wheel weight (total of 12lbs all 4 wheels). I'm sure a larger difference can be found with a larger weight difference in the wheels.

It is impossible to recreate every factor to an exact proportion save for the wheel/tire combo. As a matter of fact, it's all but impossible to run the exact same time more than once, humans don't work that way, and perameters change after each run.

To the original poster: It is impossible to calculate, but matters not anyway, if you want to see how your car and your ability has changed, take it to the track, there is no other way.
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Old 08-26-2005, 07:07 PM   #15
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All those times are way too close to attribute them to the wheel/tire combo. Thoe only way to realy know is to make about 5 runs with each combo, going with a difference combo each run to sort of make up for environmental changes that effect the numbers.

I believe where weight really counts is in twisty races. Yes, it does count in drag too, but more so on tight tracks like auto-x. You'll get the most of wheel-weight-loss benefit when accelerating from lower speeds and braking.
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Old 08-26-2005, 11:56 PM   #16
Kevin Thomas
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Quote:
Originally Posted by metoo
I believe where weight really counts is in twisty races. Yes, it does count in drag too, but more so on tight tracks like auto-x. You'll get the most of wheel-weight-loss benefit when accelerating from lower speeds and braking.

Same article as I posted above but on a road course.

16" Lap time: 1:03.7, 96.1mph straight speed

17" Lap time: 1:03.2, 95.5mph straight speed

18" Lap time: 1:03.9, 95.0mph straight speed

The 16"ers had a higher trap speed on the long straight due to being lighter and smaller in wheel diameter but was 'squishy' around the turns. The 18"ers gave the most balanced handling but it cost lap time around the corners due to acceleration. The 17"ers had the best balance between acceleration and cornering.

Like UltimateLurker stated, you have to test on your own. Your car and setup may end up with different results for different reasons. I say this because in the article I ppsted about, wheel weights were tested on the Eclipse GT as well as a No ballast, 50-lbs ballast, 150-lbs ballast and 250-lbs ballast on the Eclipse as well. The ballasts were also tested on a 2160lbs Ford Focus (Eclipse was 3050lbs curb weight). The same ballasts had much more dramatic results on the lighter Ford Focus. I'm sure the wheel weight difference would've been more dramatic as well. Every car is different.

Last edited by Kevin Thomas; 08-27-2005 at 12:01 AM.
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Old 08-27-2005, 12:06 AM   #17
subysouth
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I need to direct Uncle Scotty here. I am not surprised by the near negligible results at all.

ss
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