Ping-pong on autopilot after rear wheel replacement + wheel alignment

[DiamondHands]

Hi fam, Rocinante's right rear tire had a flat 4 weeks ago. Telsa service center popped on a loaner wheel, recommended I get both rear tires replaced, and then called me back in 3 weeks later when the tires had arrived. They popped the new tires on, and did a wheel alignment which I had asked for.

I hit the highway after the SC visit, engaged autopilot, and immediately noticed the ping-pong effect. Additionally, Roci would markedly stutter while changing lanes on AP.

As I drove Roci back in to the SC yesterday, admittedly the ping-pong effect wasn't as strong as it had been in the week past. Sure enough, the SC manager and his tech claimed they didn't really notice the ping-pong that much. They did say they noticed some vibration (no idea what they're talking about), and would test the ultrasonic sensors.

While I wait for the SC to figure things out, I thought I might share what's been happening with you all. One "fix" I found on the forum was someone having had all 4 tires replaced to alleviate the ping-pong issue. Not sure why this would have worked. I've had 2 tires replaced before (as opposed to all 4), and never had the ping-pong issue.

For some reason I'm unable to post videos here. So I'm including links to the videos I had posted on Twitter.

https://twitter.com/x/status/1378843716224491520

https://twitter.com/x/status/1378842351959965698

EDIT:
Roci was running 2021.4.12 before and after the SC appointment. She's got HW3/AP2 with FSD package.

 

[cobra]

I'm going to guess alignment followed by balancing. The only thing that sounds like it changed in the front end is alignment. I'm new to our Tesla, do SC's do 4 or 2 wheel alignment? Sounds like it has to be 4 if you only replaced rear tires?

So either sloppy alignment or the car has to relearn front steering offset related to the cameras?

 

[ngng]

i suspect it is some combo of:
a) worn front tires, brand new rear tires
b) alignment (not necessarily bad, just different)

 

[aymelis]

Hi DiamondHeads, did you figure this out ? I just changed my back tires and Autopilot is swerving in straight lanes and hardly keeps the lane on windy roads. Was it an alignment issue ? Thanks

 

[DiamondHands]

Hi DiamondHeads, did you figure this out ? I just changed my back tires and Autopilot is swerving in straight lanes and hardly keeps the lane on windy roads. Was it an alignment issue ? Thanks

Hey buddy, sorry for the late reply, the issue sorted itself out after several days of driving. I suspect the car perhaps needed to re-calibrate.