04-28-2021, 03:10 PM | #1 |
Drives: 2021 Camaro V6 1LT 1LE Join Date: Aug 2020
Location: NC
Posts: 2
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Wheel setup for track use
Hi all,
I currently have a stock 2021 V6 1LT 1LE, which comes with 8.5" et 25 wheels with 245/40R20 tires in the front and 9.5" et 39 wheels with 275/35R20 tires in the rear. I'm looking to get a second set of wheels and tires for track days and time trial events in my area, and due to SCCA classing rules, the max tire width I could go with is a 285 to stay in my Sport 3 class. I'm looking for a square setup, and have my eyes on a set of 20"x10" et 25 wheels, and 285/35R20 tires on all four corners. I was thinking the 35 sidewall profile would be ideal, due to having the closest overall wheel diameter to the stock wheel/tire setup. However, I have a few concerns with fitment/clearances/rubbing. After trying to do some research on the forums, I see a lot of people running 285/30R20s vs the 35s, but have seen multiple users with the 35s as well. And while I've seen multiple posts showing their 20"x10" et 25 wheels, specifically in the front, it seems like et 23 is the accepted value. I want to ensure this setup will work and fit without any rubbing of any sort, especially during sustained track time. Do you think this setup will work? Or do you have any other recommendations? All help is appreciated!! Thanks guys!! |
04-28-2021, 03:50 PM | #2 |
Drives: 2017 Camaro 2.0T, 91 Miata Join Date: Jan 2020
Location: Raleigh, North Carolina
Posts: 505
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I think that should be fine. They will be slightly taller than the stock 275s but shouldn't be enough to cause an issue.
As far as width/offset, you'll be good. I run a 19x10.5 et 22 all around with 305/30-19 and don't have any issues with rubbing. It's possible you'll run into issues with getting the max camber, but that's all I would foresee, if at all.
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04-28-2021, 04:22 PM | #3 |
Drives: 2018 Camaro 1SS 1LE Join Date: Sep 2018
Location: Front Range, CO
Posts: 1,868
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I can't make any recs based on experience but FWIW, I recently ordered smaller diameter wheels to save weight vs the 20s. I think you could run 285/30/19 or 285/35/19.
I run 265/40/19 square for winter w/ no issues. Stability controls work fine.
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04-28-2021, 09:50 PM | #4 |
Drives: Chevrolet SS 1LE Join Date: Oct 2019
Location: St. Charles, MO
Posts: 1,446
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A 285/35/20 is 27.9" in diameter. That's taller than the 1LE tires, front or rear. There is no advantage to running tall tires on a road course or autocross. It will raise your car's CG and instant centers, which means your car will ride a good bit higher and transfer more load during any form of acceleration. That's usually good for a drag launch but it's bad for cornering and braking. Plus they will be heavy. I would strong recommend going down to 285/30/19 front and rear, which is 25.7" in diameter. Your car will literally sit more than an inch lower on those tires which is meaningful in reducing weight transfer, plus they will be a lot of pounds lighter.
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Matt Miller
2020 SS 1LE |
05-23-2021, 03:09 PM | #5 | |
Drives: 2021 LT1 10 speed auto Join Date: May 2013
Location: Connecticut
Posts: 2,343
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05-23-2021, 07:59 PM | #6 | |
Drives: Chevrolet SS 1LE Join Date: Oct 2019
Location: St. Charles, MO
Posts: 1,446
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The tradeoff is that a taller tire of course increases your overall gear ratio (lowers it numerically), which may not be a good thing. You ideally want to cross the line near the top of 4th or maybe 5th, so you have to work that part out. I don't know for sure about removing the sway bar on a car like this. Unlike the front, I don't think the rear bar would be an issue for limiting travel. And with the IRS on these cars, there's no issue of solid-axle twist to address. So I'm think you can just leave connected, but maybe someone else has real experience drag racing these cars would have a different opinion.
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Matt Miller
2020 SS 1LE |
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05-24-2021, 07:32 AM | #7 | |
Drives: 2021 LT1 10 speed auto Join Date: May 2013
Location: Connecticut
Posts: 2,343
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05-24-2021, 08:02 AM | #8 | |
Drives: Chevrolet SS 1LE Join Date: Oct 2019
Location: St. Charles, MO
Posts: 1,446
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If uneven (left to right) traction due to uneven loading of rear tires were an issue, then a rear bar could help. On a solid-axle car, it would help prevent the unwanted tendency to pick up the right tire and plant the left, and you could even preload it to counter that. But with an IRS car, that shouldn't be an issue. Squat is not a cause of weight transfer - it's the result of it. But it does reduce traction during a launch because the full amount of weight transfer won't happen until the suspension has reached its static point - i.e., until it's done getting into its "squat position." So while the suspension is moving toward its final squatting position, the rearward weight transfer is not fully loading the rear tires. So for a standing-start launch, the less squat the better. This is why cars set up for drag racing have stiff springs and lots of compression damping rate on the rear. Some, like Top Fuel cars, have no rear suspension at all! They get all the extra traction from weight transfer instantly. The problem is you don't really want to drive around the street like this. And it is possible to create suspension geometry with more than 100% squat (a lot more possible with a solid axle than IRS), that actually causes the rear end to rise up with power application rather than squat. This helps plant the rear tires by pushing up on the mass of the car. But you can't do that with a sway bar, and again this isn't good for cornering.
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Matt Miller
2020 SS 1LE |
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05-24-2021, 01:07 PM | #9 | |
Drives: 2021 LT1 10 speed auto Join Date: May 2013
Location: Connecticut
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05-24-2021, 02:16 PM | #10 |
Drives: Chevrolet SS 1LE Join Date: Oct 2019
Location: St. Charles, MO
Posts: 1,446
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Sure. So changing front or rear ride height doesn't significantly change the loading on either set of tires. Weight doesn't "slide" on the chassis rake, if you know what I mean. Lifting the front end might help launch the car just because it would raise the CG, though. That would cause more weight transfer to the rear tires on launch. Again, this would be terrible for braking or cornering. Lowering the rear shouldn't help at all.
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Matt Miller
2020 SS 1LE |
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