Authenticity of my Bertoia Side Chairs?  

Pads look
Pads look totally fake. If thats the case then the chairs probably are. Why would anyone go through the trouble of faking pads for an authentic chair?

FYI, I removed the back pads...
I removed the back pads and left the bottom pads. They are made of cowhide and look like these (not where I purchased):
http://hivemodern.com/products/?view=sub_product&sid=679

I stand
Corrected. I'd never seen those pads before.

Stamp?
I think I had heard that there is a Knoll stamp somewhere on the chair, but I have not looked at a recent production chair myself to verify this.

K stamp
I got a response from Knoll customer service:
"Knoll started stamping a K into the base of the chair in the early 90's. If the chair was produced before the 90's the only way to authenticate would be an original sales receipt or certificate of authenticity."
I can't seem to find this stamp on my chairs, purchased in 2002, but I may be looking in the wrong place. The dealer I purchased them from uses the Knoll logo in the online listing for other Bertoia chairs but not for the side chairs yet I asked and they say the side chairs are Knoll. I just sent a message to Knoll customer service asking them to be more specific about the location of the stamp.
Anyone find a K stamp on their Bertoia side chairs?
I wish I didn't lose the paperwork.

I don't think it's a knoll...
Because in the last pic you can see that the wires coming from the seating part to the front edge are welded under the peripherical wire, and the ones on the side are welded on top of it. On the knoll ones, i think that the edge-wire is always under all the other ones...on all sides of the chair...at least it's so an all the vintage ones i've seen.

from Knoll website
My suspicion is that the chairs are authentic since those pads are unique to Knoll.
I don't know why someone would put those pads on reproduction chairs and then try to sell them, since the pads alone probably cost more than the reproduction chairs.

Wires under
The wires on authentic chairs are indeed welded on the underside. It seems terribly inconvenient of Knoll not to put a stamp somewhere on the leather pads. Lord knows they are fond of stamping KNOLL on just about every other surface of their textiles.

It looks like my authentic se...
It looks like my authentic set of Bertoia side chairs.

whitespike?
your bertoias have the welds under the peripherical wire at the front edge?

Wires
All the wires (horizontal and vertical) lay on top of the frame, except at the front edge of the seat. At the front edge, the vertical running wires lay underneath the frame.
See pic linked below.

Believe so, I can check...
Believe so, I can check again later.

well, it seems that...
...they've changed that at some point of the production because on my vintage ones (with some knoll stickers left) and all the others i've seen, they are clearly all on top...Which is quite uncomfortable btw.
So i guess then that yours are genuine because as someone said, the pads would be worth more if they weren't.
I'm happy, I learned something new today, thanks.

All the wire welds are on top...
All the wire welds are on top EXCEPT the front welds on mine.