I stored two cars for a total of 31 months in an enclosed, unheated garage, back in 1989-1992. 1966 Coronet 500 and 1972 Satellite Sebring. Long-term storage is obviously a different deal than just six months or so. Do NOT store on jackstands on the unibody jacking points. I stored both in the air to the point where the tires were about an inch off the ground, putting wood blocks under the axle at the spring, and up front, under the A-arms, with the suspension fully loaded. No benefit is gained with letting the suspension hang - this is not the normal state of the suspension, anyway! I also put 36# of air in all of the tires. The plastic water vapor barrier is a great idea, whether it is parked on concrete, dirt or gravel.
If you are storing for six months or less, there really isn't a lot to worry about, other than keeping the environment as dry as you can. Store with a full tank of fuel, and use Sta-Bil or similar product to help preserve the crappy fuel we deal with, these days. I also would disconnect the fuel line at the inlet side of the pump after you have run the car to fully warm up, then start the car and run the fuel out of the pump to the carb so it stalls and dies. No worries about a gunked-up fuel line or crap in the carb(s). You'll change the filter before you start the car back up, anyway.
The longest I've let my cars sit has been roughly a year or less. My '69 D300 had been off the road for probably a decade or more. The fuel line was 100% filled with a nasty tar that indicates a LONG time of inoperability. This was from the pump inlet back to the point where the line went up the tank outlet. The pump had been replaced before I got the truck, so the line from there to the carb was new. Replaced the line from the tank to the pump, and replaced the old tank with an excellent used tank. One filter before the pump, and one before the carb. Now, the truck runs great...but I have an inop fuel gauge now. Yay.
now a car with specialty/soft tires or racing slicks etc.
a lil' different story
not good to store in one place for any real period of time
rotate the tires often, so they won't flat-spot or distort
or absorb whatever from concrete or gravel/dirt etc.
Like RC
@Richard Cranium
I've stored long term or even just parked on carpeting
& aired up tires to like 40psi, for winter storage
haven't noticed any flat spotting either
was only about 11 months, the longest
too many projects at the time
BFG TA Radials some 14-15 years old now
I'd think if you're worried about the suspension
store it with some weight on the suspension/cribbing,
carpeting, cardboard or wood etc.
something to isolate the tires from dirt or concrete
& have the majority of the weight on the jack stands
that's my logic/thinking anyway
worked well for me for the past 47+ years
of driving/storing cars/bikes, racecars 4x4's etc.
your opinions & outcomes may vary
