Vibration
Thread Starter
Le Mans Master
Joined: Jun 2016
Posts: 5,470
Likes: 4,036
From: Cincinnati, OH
Vibration
2019 GS with now 10k mi still has the factory run-flats.
When I first bought the car it had stock wheels/stock tires. In fear of cracking a stock wheel I have swapped to a used set of Forgeline F01 wheels from a local autocrosser. Wheels were then found slightly bent and repaired (I confirmed seeing the rear barrel out of round when spinning on jackstands).
Never had a vibration (that I could tell) with stock wheels and now these Forgelines are supposed to be "fixed". What are the odds that the 2019 date code run-flats are the issue? They have plenty of tread, but may be "aged out". Never dealt with run-flats before.
The local wheel repair shop said they ensured the wheels were "straight" but once they put the rear tires on, they got worse...still "balanced out" though. I can feel a vibration at 50mph and 80mph presumably from the rear as I don't feel anything in the steering wheel.
Just took a 1600mi trip and staying to 80-85mph made it slightly annoying that it wasn't nice a smooth ride. Cruise set to 80 the vibration would almost be cyclical... on for 2 sec then off for 2 sec. Strange.
When I first bought the car it had stock wheels/stock tires. In fear of cracking a stock wheel I have swapped to a used set of Forgeline F01 wheels from a local autocrosser. Wheels were then found slightly bent and repaired (I confirmed seeing the rear barrel out of round when spinning on jackstands).
Never had a vibration (that I could tell) with stock wheels and now these Forgelines are supposed to be "fixed". What are the odds that the 2019 date code run-flats are the issue? They have plenty of tread, but may be "aged out". Never dealt with run-flats before.
The local wheel repair shop said they ensured the wheels were "straight" but once they put the rear tires on, they got worse...still "balanced out" though. I can feel a vibration at 50mph and 80mph presumably from the rear as I don't feel anything in the steering wheel.
Just took a 1600mi trip and staying to 80-85mph made it slightly annoying that it wasn't nice a smooth ride. Cruise set to 80 the vibration would almost be cyclical... on for 2 sec then off for 2 sec. Strange.
Melting Slicks
Joined: May 2007
Posts: 3,251
Likes: 768
From: Lindenhurst, IL
I had a similar problem with a set of i-Forged wheels that I had on my C6. Everything checked out fine on the road force balancer; but I could never completely eliminate the slight shaking in the steering wheel.
I ended up moving those tires to a new set of wheels. Everything was perfect. I threw the i-Forged wheels in the trash because I didn't want anyone else to have the same problem.
My theory was that the lug holes were bored slightly off center. Since the balancer is typically mounted using the center bore, it didn't show up on the balance.
Anyway....my bet is that your problem is in at least one of the wheels.
Moral of the story.....switching to fully forged does not guaranty that your wheels won't bend or crack. It happens to even the most expensive wheels.
I ended up moving those tires to a new set of wheels. Everything was perfect. I threw the i-Forged wheels in the trash because I didn't want anyone else to have the same problem.
My theory was that the lug holes were bored slightly off center. Since the balancer is typically mounted using the center bore, it didn't show up on the balance.
Anyway....my bet is that your problem is in at least one of the wheels.
Moral of the story.....switching to fully forged does not guaranty that your wheels won't bend or crack. It happens to even the most expensive wheels.
Thread Starter
Le Mans Master
Joined: Jun 2016
Posts: 5,470
Likes: 4,036
From: Cincinnati, OH
Thanks for the feedback. I was excited to get into the Forgelines for the quality....but after visually seeing a out of round rear wheel I was pretty surprised...
I might do the tires over the winter as they are 6 years old and given their use (not a econo-box car) it may be a safe bet to replace them. If I still have a vibration I won't be a happy camper...wheels are NOT cheap...
I might do the tires over the winter as they are 6 years old and given their use (not a econo-box car) it may be a safe bet to replace them. If I still have a vibration I won't be a happy camper...wheels are NOT cheap...
6th Gear
Joined: Sep 2021
Posts: 6
Likes: 2
From: michigan
2018 Stingray bought 4 years ago at 9K miles. I have the same 2 second on-off slight vibration between 65-75 mph. Only noticable on very smooth roads. Started with brand new Michelin all season run flats that I installed when I took delivery of the car. Two times road force balance at different shop, no improvement. I believe it is a harmonic imbalance in the drivetrain issue, not correctable. Seems like a lot of similar issue like this posted.
Racer
Joined: May 2015
Posts: 475
Likes: 300
From: Utah
You need to have a road force balance done. A tire can have perfect balance and yet
have a high road reading which can lead you to believe there is a balance or wheel
problem or even a torque converter issue on a8's.
I have had two brand new MPSS replaced due to high road force readings. My tire guy
says a reading over 15 and you will feel it, especially in a sports car.
The RF reading discovers imperfections under the tread related to the assembly of
tire belts and is irreparable.
have a high road reading which can lead you to believe there is a balance or wheel
problem or even a torque converter issue on a8's.
I have had two brand new MPSS replaced due to high road force readings. My tire guy
says a reading over 15 and you will feel it, especially in a sports car.
The RF reading discovers imperfections under the tread related to the assembly of
tire belts and is irreparable.
Race Director
Joined: Aug 2015
Posts: 12,264
Likes: 4,755
From: SE WI
2018 Stingray bought 4 years ago at 9K miles. I have the same 2 second on-off slight vibration between 65-75 mph. Only noticable on very smooth roads. Started with brand new Michelin all season run flats that I installed when I took delivery of the car. Two times road force balance at different shop, no improvement. I believe it is a harmonic imbalance in the drivetrain issue, not correctable. Seems like a lot of similar issue like this posted.
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Thread Starter
Le Mans Master
Joined: Jun 2016
Posts: 5,470
Likes: 4,036
From: Cincinnati, OH
I just got back from the tire shop and a friend I trust...
Front 1 was out 0.25 oz
Front 2 was out 1.25 oz
Rear 1 was out 0.75 oz and the barrel still slightly bent
Rear 2 was out 1.25 oz
It is MUCH better now even up to 120. But at 60mph I can still feel a slight cyclical vibration that is on/off. I'll live with this for now given the cost of wheels or tires.
So two issues I have, the wheel repair place did a poor job at fixing the wheel and secondly couldn't balance it for ****.
Front 1 was out 0.25 oz
Front 2 was out 1.25 oz
Rear 1 was out 0.75 oz and the barrel still slightly bent
Rear 2 was out 1.25 oz
It is MUCH better now even up to 120. But at 60mph I can still feel a slight cyclical vibration that is on/off. I'll live with this for now given the cost of wheels or tires.
So two issues I have, the wheel repair place did a poor job at fixing the wheel and secondly couldn't balance it for ****.
Last edited by smitty2919; Aug 9, 2025 at 05:19 PM.