Having endured several loooooooong Canadian winters being parked for inhumane periods of time......
Covered tires for up to 6 months have presented no severe issues so far.
What is important is what the tires are parked on.
Grass, mud, dirt......all bad.
Asphalt.....I’ve read as being bad, because of oils and such leaching into the rubber of your tires.
Hardwood 2x12” boards is good.....tires completely ON the board.
Concrete I’ve read is good.....no leaching.
Good sized gravel is best because it allows good air circulation and drainage.
RV antifreeze life expectancy.......not sure on that one.
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Ken and Terry
2018 Sunseeker 2430S-CD, nicely modified and carried by a 2017 Ford E450 Sport
Former Georgetown 330TS owner for 10 years with more mods than I can count