viiv

Once the temperature gets low enough, that you run the risk of city crews deploying salt, and you run the risk of unknowingly driving over it and getting it all over your Z.

It's not daytime temperatures you should be concerned about; but night time low temperatures.

I make sure to get my Z off the road before the first night where the temperature dips below 4°C (40°F). If you don't, you are going to be spraying salt (and salt dust, and maybe even brine) all over the undercarriage of your beautiful Z.

While some city crews may start deploying salt with nightly lows at closer to 0°C, there's no way to know for sure what level of discretion they use to decide at exactly what temperature threshold to do it at. Some city manager in a certain area that you will drive through may order the roads salted with just a 3°C nightly low, so I play it safe. I cut off the Z with 4°C nightly lows... to never see the road again until April or May, after at least a week or two of steady rainfall to wash away the winter's worth of salt.

PS. I find private property managers can be even more over-zealous than the city crews. The first place I always see salt every fall is a mall near my house where they start deploying huge amounts of salt all over the mall parking lot when nightly lows hit just around 3-4°C. I'm guessing they really don't want to see a lawsuit due to a accident on their property.