Track results 18s vs 20s.

[SUX2BU]

I wasn't sure if this would go here, in the dragstrip section or wheels section, but feel free to move it where it belongs Mods.


Long story short: swapping to 2.0" shorter front, 1.5" shorter rear and 66 lb lighter wheel/tire combo is worth about 2 tenths and 2.426 mph in the 1/8 mile and about .364 seconds and 2.887 mph in the 1/4 mile.


Ok, so I wanted to do a back to back test of some stock 20" SS/RS wheels vs my 66 lb lighter weight Forgestar F14 18x8.5/18x11 wheels, but I could not find someone to loan them to me or swap me at the track (I would still LOVE to do a more accurate back to back same day at the track if anyone wants to help out with some wheels). So what I did was take the last time I was at the track and compare them to my times last night. I have corrected all times with a DA calulator to even out the weather/altitude differences. The ONLY change to the car was the addition of my Forgestars. The stock wheels times were at an 1/8 mile track so i had to calculate my 1/4 mile times using all my previous time slips, not some inaccurate online calculator.

Stock wheels on stock Pirellis:
60 ft: 2.279
330 ft: 6.027
mph:63.41
1/8: 8.981
mph: 82.74
DA: 3,832 ft

Corrected time/mph: 8.561 @ 86.856 13.003 @ 111.278 (calculated estimate of corrected 1/4 mile after analyzing all my time slips)


Forgestar F14 wheels with regular street tires (not drag radials):
60 ft: 2.206
330 ft: 5.819
mph: N/A
1/8: 8.715
mph: 85.60
1,000 ft: 11.164
1/4: 13.205
mph: 110.79
DA: 3,351 ft

Corrected time/mph: 8.361 @ 89.282 and 12.669 @ 114.165

[LoneStar]

Makes a nice difference! But don't you also have drag radials on the Forgestars? Was the run with the stock 20" wheels on the Pirelli tires?

[BackinBlackSS/RS]

WOW!! I knew it made a difference, but that is amazing. Switch to 18's
and whip those 5.0's all day long.

[zebra]

yeah, and besides... 18s look better

[Lumix]

Originally Posted by zebra

yeah, and besides... 18s look better

If they made the RS wheels in 18 inch size, I'd be first in line to buy them.

[Rahtok]

Do the Camaro's have a way of reprogramming the speedo to take into account the smaller circumference?

Follow on question: By changing the front and rear ratios differently, how does the ABS and Traction Control unit fare? I know this was an issue for other cars and their ECU in the past.

Great results though -- you'll probably find some mild MPG gains with that loss of unsprung weight as well.

[KMPrenger]

Damn..and thats in the 1/8 mile. Wouldn't that equate to possibly 3 or 4 tenths better in the 1/4 mile?

[BackinBlackSS/RS]

Originally Posted by KMPrenger

Damn..and thats in the 1/8 mile. Wouldn't that equate to possibly 3 or 4 tenths better in the 1/4 mile?

Yep, he's got 1/4 results also posted.

[SUX2BU]

Originally Posted by LoneStarCamaro

Makes a nice difference! But don't you also have drag radials on the Forgestars? Was the run with the stock 20" wheels on the Pirelli tires?

Not on these. I have my regular street tires. I am still waiting on my second set of 18x11s to mount my 315 drag radials. I wouldn't try to compare street tires to drag radials. Yes the 20s had Pirellis.

Originally Posted by Rahtok

Do the Camaro's have a way of reprogramming the speedo to take into account the smaller circumference?

Follow on question: By changing the front and rear ratios differently, how does the ABS and Traction Control unit fare? I know this was an issue for other cars and their ECU in the past.

Great results though -- you'll probably find some mild MPG gains with that loss of unsprung weight as well.

Oh, it feels 100x better driving around with light weight wheels. Car feels so much lighter and more responsive. Feels like I'm driving a sports car and not a fast tank.
Yes, you can tune for a smaller diameter rear tire (the rears control the speedo). For the ABS computer to throw a code it has to see a difference of 6% between any two wheels. With my size tires I am only at about 2.2% difference between the front and rear.

Originally Posted by KMPrenger

Damn..and thats in the 1/8 mile. Wouldn't that equate to possibly 3 or 4 tenths better in the 1/4 mile?

If you reread my first post it is a .2 difference in the 1/8 mile and a .364 difference in the 1/4 mile.

[KMPrenger]

Originally Posted by SUX2BU

Oh, it feels 100x better driving around with light weight wheels. Car feels so much lighter and more responsive. Feels like I'm driving a sports car and not a fast tank.....

If you reread my first post it is a .2 difference in the 1/8 mile and a .364 difference in the 1/4 mile.

Oh man...I should have seen that. My bad.

I'd love having smaller/lighter rims....but damn (in my opinion) the car just doesn't have the same flair as with the 20s.

Only option would be going to expensive lightweight 20" wheels......keyword for me is 'expensive'. I don't Auto X, and hell I don't even have a 1/4 mile track near me so hard to me to justify the expensive wheels.

[Padre]

Great info! I love my 18's. And they do look better too.

Padre

[squat]

Great info, I didn't know that 18s would fit over your brembos

[suplex]

Originally Posted by Lumix

If they made the RS wheels in 18 inch size, I'd be first in line to buy them.

I truly don't know why they don't. It doesn't make any sense at all, I would love to have the 18" wheels on my 1LT styled the same way as the 20" RS wheels.

[Flatsix Racer]

Very interesting...