Max weight on Eames lounge & shock mounts?  

chair is not the problem
The problem is not with the chair, the problem is with the people. You are correct that when the chair was designed there people were not as many obese (fat - corpulent - stout - plump - pursy - gross - portly) people. Height is not the issue.

Pedley,As beautiful as a...
Pedley,
As beautiful as a lot of the Eames stuff looks, the fact is that they are actually pretty badly designed.
A chair as fragile as the lcw/dcw/670/ect that requires new shockmounts every 20 years under normal usage is not a good design. The larger the person, the faster its likely going to develop breaks.

Max weight on Eames lounge & shock mounts?
I recently acquired a used Eames lounge. I'm guessing it's late 70s/early 80s vintage: Greyish rectangular Herman Miller labels, 5-ply rosewood, slides on the head cushion, etc. It seems to be in very good shape, with minor wear on the leather, almost no scratches on the wood or metal.
I'm a little concerned about flex in the back, and I'm having a hard time trying to figure out whether it's just the way the chair is, too much wear on the shock mounts, or too heavy a person sitting in it. (Both people who have sat on it are well over 200lbs, one probably closer to 275.)
So, two questions: Is there a "max" weight you all would think this chair would have? (I realize that back in the 50s when this was designed, people over 6'5 and 250 weren't as common as they are today, so I'm wondering...)
Also, is there a reliable way to assess whether the shock mounts are in good shape or the back is tilting back too far?
Thanks!

Pedley, if you unscrew the armrests and pop them off and then unscrew the metal armrest plates you will be able to physically inspect the shockmounts and determine how secure they are.

spacepirate,
in defense of the eames, there was no way to forsee how new techniques and materials would age over the decades. another example is the foam that was used in the 50s and 60s and that hardened over the years (as in the jacobsen swans e.g.).
also there are many chairs with original, stable shockmounts around. 20 years? more like 50, that's how long the shockmounts on my chair lasted and that's not too bad if you ask me. it should also be taken into account how well or or bad a chair was treated by the preowners and there is often no way how to tell that...
it's also a given that old furniture must be treated with care, so the weigt of the user can be a problem, of cause.