The dangerous world of Reel-to-Reel Tape

how long do recorded magnetic tapes (here: R2R, but also 8 track, cassette, VHS, etc) LAST before they loose their information?

@kraftwerkturbo That depends on storage. They need to be stored in a low humidity environment to prevent shedding of the oxide on which the recording exists. It that is done the tape will last decades with ease.

For this reason its better to store tapes in an attic rather than a basement! Its also a good idea to store the tape in a plastic bag in its box, along with a packet of Silica Gel.

@kraftwerkturbo It depends.

I purchased a case (10 reels) of Maxell 35-180 UD tape in 1981.  A few years later, I purchased two cases (20 reels) of "Ampex GM-3600 Grand Master Professional Recording Tape." 

From the mid 90’s to the mid 2000's, my R2R sat mostly unused, but I would play a reel on rare occasions.  Around the mid 2000’s, I noticed my Ampex tapes started to sound muddy and were leaving a lot of residue on the tape heads, pinch rollers, and transport mechanism so I had to stop using them (because they sounded like crap).

My Maxell reels are still playing just fine.

I was referring to the lifetime of the RECORDINGS ON the tape. I heard that also vibrations (for example keeping it in the car) will erode the quality and reorient the magnetic particles. My VHS tapes (20 years?) have lost pretty much everything, barely useable. 

When my Ampex tapes went bad, I found out they were very prone to SSS (Sticky Shed Syndrome) SSS Syndrome. List Of Known SSS Tapes.

If you have the time and are willing to put up with the maintenance then go for it.

Enjoy