Tesla in Park suddenly moved forward [air temp 33, snow on ground, parked on incline, OEM tires]

[illYay1337]

Physics or no physics though, no one else had trouble with their car rolling forward.

I have dual motor so I can go into the mountains and My friend’s 2wd had no issue even getting out of the driveway.

I absolutely had to use slip start. My car was swerving side to side as I struggled to reverse out of the driveway with it on. With it off my car wouldn’t budge. I had to make everyone else move their cars out of the way so I didn’t hit anyone. Not a fun experience when you arrive at Tahoe at midnight.

 

[DaveRZ]

Tires make all the difference, not just in snow, but anytime the weather is cold. For example, if you have "summer" tires, they'll slip and slide on a completely dry road when its 30 degrees out because the rubber will harden up and lose grip.

Do you have (at least) all season's on your M3? Do they have decent tread left? And lastly, what do you have them inflated to? remember that your tire pressure will go UP slightly as you go up in altitude, so that will reduce the tire's contact patch with the ground. Less contact patch, less grip.

I totally sympathize with your car being the only one sliding around (though that can be fun in the right circumstances).

Others have already stated that the factory MXM4's are bad in the snow, and if yours are also worn and a bit overinflated, that would explain your inability to gain enough traction to keep you from sliding around.

 

[illYay1337]

Lol actually I am overinflated. The gas station tire pump was inaccurate and my car reports them as higher than what I thought I was filling them with. I’ve been meaning to deflate them.

I have the stock tires too which I know isn’t great for snow. My friends had regular tires too though. It’s rare to have snow in CA outside of going alone ski trips so I don’t know many people who switch to snow tires.

 

[batteries]

I had the same problem occur a couple of days ago: Pulled into my friends very steep snow and ice covered driveway, stopped the car, put into park and went in to the house for a cup of coffee. About 3 minutes later we watched the car skid backwards down the driveway for about 50 feet until coming to a stop. The front of the car was pointing up the hill, the car slid backwards down the hill, and the front wheels were rolling and the back wheels were skidding. I'm not sure why the car stopped. Maybe there ratio of snow to ice increased slightly and there was more traction? The bottom line: it was a terrifying sight. If the car would have slip another 30', it would have slid into a bust roadway. I'm now afraid of exiting the car when parked on a steep/icy driveway for fear that I the car sliding backward could trap me underneath the door. And why the delay before the car started sliding? Or what if there are children playing in the driveway. There is nothing OK about this situation.

 

[AlanSubie4Life]

I had the same problem occur a couple of days ago: Pulled into my friends very steep snow and ice covered driveway, stopped the car, put into park and went in to the house for a cup of coffee. About 3 minutes later we watched the car skid backwards down the driveway for about 50 feet until coming to a stop. The front of the car was pointing up the hill, the car slid backwards down the hill, and the front wheels were rolling and the back wheels were skidding. I'm not sure why the car stopped. Maybe there ratio of snow to ice increased slightly and there was more traction? The bottom line: it was a terrifying sight. If the car would have slip another 30', it would have slid into a bust roadway. I'm now afraid of exiting the car when parked on a steep/icy driveway for fear that I the car sliding backward could trap me underneath the door. And why the delay before the car started sliding? Or what if there are children playing in the driveway. There is nothing OK about this situation.

Do you have proper winter tires or just the stock tires?

They should add parking brakes to the front wheels! Maybe they will some day - this is going to increasingly become an issue with EVs (RWD ICE vehicles are quite rare and AWD & FWD ICE don't suffer from this issue unless it is extremely slippery indeed).

Delay: takes time for your warm tires to melt and create a nice layer of liquid.

All well covered in the owner's manual but definitely something to be aware of. Strongly recommended to have a set of wheel chocks in the emergency kit, and use them in high risk situations (maybe have someone else place them (I guess the front wheels would make sense) while your foot is still on the brake).

In many cases you can place the rear wheels on a less slippery or less sloped surface (reverse the car orientation). That may help too.

 

[rpiotro]

I experienced the same thing. Set it in park, waited then exited the car. Walking up my driveway I watched my car slowly slide toward the street. The rear tires were locked. It just was simply slippery. No fault of the car. Any other car would do the same. It stopped when it hit bare pavement at the bottom before it got to the street.

 

[dmurphy]

I’ve woken up and found my wife’s (pre-Tesla) AWD SUV in the street before. Slid all the way out of our driveway. It’s not overly steep - just a few degrees - but it’s enough that if a coating of ice forms under the tires, it can be a skating rink.

Doesn’t help that we have a paver stone driveway, so we don’t salt it.

I’ve learned to use chocks when we expect icing.