2020 GLC63 - My first problem?
Thread Starter
Member
Joined: Jan 2019
Posts: 150
Likes: 36
2003 Cobra / 2018 GLC300 / 2020 GLC63 SUV
2020 GLC63 - My first problem?
So I had my rear snow tires mounted today (long story but was driving with two front snows and the stock PS4P in the rear). I'm running Pirelli Winter Scorpion 295/40R21. When I accelerate from 30-50 or 50-70, the traction control engages and I can feel the rear diff' trying to control power deliver to both rear wheels. It feels like the car is swaying back and forth, almost like i'm driving on a flat tire (tire pressures are all normal). At slower speeds, it does not exhibit this behavior. Roads are dry and I can guarantee now wheel spin. Does it in all driving modes, but more so in Comfort. Turn Traction Control off, the problem goes away.
Anyone else had this behavior with snow tires?
The only thing I can think is that the car came with 295/35 R21's; even though the dealer ordering guide from July has the stock 21 size as 295/40 R21s. Could this be causing the problem?
Anyone else had this behavior with snow tires?
The only thing I can think is that the car came with 295/35 R21's; even though the dealer ordering guide from July has the stock 21 size as 295/40 R21s. Could this be causing the problem?
Senior Member
Joined: Nov 2005
Posts: 410
Likes: 176
2020 GLC 63
So I had my rear snow tires mounted today (long story but was driving with two front snows and the stock PS4P in the rear). I'm running Pirelli Winter Scorpion 295/40R21. When I accelerate from 30-50 or 50-70, the traction control engages and I can feel the rear diff' trying to control power deliver to both rear wheels. It feels like the car is swaying back and forth, almost like i'm driving on a flat tire (tire pressures are all normal). At slower speeds, it does not exhibit this behavior. Roads are dry and I can guarantee now wheel spin. Does it in all driving modes, but more so in Comfort. Turn Traction Control off, the problem goes away.
Anyone else had this behavior with snow tires?
The only thing I can think is that the car came with 295/35 R21's; even though the dealer ordering guide from July has the stock 21 size as 295/40 R21s. Could this be causing the problem?
Anyone else had this behavior with snow tires?
The only thing I can think is that the car came with 295/35 R21's; even though the dealer ordering guide from July has the stock 21 size as 295/40 R21s. Could this be causing the problem?
Thread Starter
Member
Joined: Jan 2019
Posts: 150
Likes: 36
2003 Cobra / 2018 GLC300 / 2020 GLC63 SUV
To clarify, the car acted normally when I had two snow fronts and two summer's in the rear. Now with the snows in the rear i'm getting the weird traction control behavior. It looks like the tire size difference is causing the problem. I was going to throw my summer wheels on to see if that removed the problem but i can't find my lug key..... the dealership must have kept it.. since its not in either glove box or in the tire repair kit.
Senior Member
Joined: Nov 2005
Posts: 410
Likes: 176
2020 GLC 63
To clarify, the car acted normally when I had two snow fronts and two summer's in the rear. Now with the snows in the rear i'm getting the weird traction control behavior. It looks like the tire size difference is causing the problem. I was going to throw my summer wheels on to see if that removed the problem but i can't find my lug key..... the dealership must have kept it.. since its not in either glove box or in the tire repair kit.
Also tire sizes vary from one brand to another, just because the numbers match, actual measurement might not be the same.
https://www.caranddriver.com/feature...tire-sidewall/
As for the dealer keeping your wheel lock, it's possible. It shouldn't happened since the tech should have all lock combos (usually a few) in his tool box, but sometimes they lose them and have to use yours. Just let the dealer know and if they can find it, they should get you a new one.
Senior Member
Joined: Nov 2005
Posts: 410
Likes: 176
2020 GLC 63
For 21"
Front: 265/40R21 and Rear: 295/35R21
Click on the specs and the "overall diam" is 29.3" and 29.1"
https://www.tirerack.com/tires/tires...V&autoModClar=
For 20"
Front: 265/45R20 and Rear: 295/40R20
"overall diam" is 29.4" and 29.3"
https://www.tirerack.com/tires/tires...V&autoModClar=
As long as the Overall Diameter ratio between the fronts and back similar (the fronts 0.1" - 0.2" taller than the back) you should be fine.
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Thread Starter
Member
Joined: Jan 2019
Posts: 150
Likes: 36
2003 Cobra / 2018 GLC300 / 2020 GLC63 SUV
I swapped back to 295/35R21 rear tires and traction control issue resolved.
Anyone want two 295/40R21 Pirelli Winter Scorpions on the cheap? They only have a couple hundred miles on them....
Anyone want two 295/40R21 Pirelli Winter Scorpions on the cheap? They only have a couple hundred miles on them....
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