I am paranoid about my knees so have spent countless hours searching and searching for such a thing. My main problem is that generally the damn things are going to be too short in the leg.
I do own a pair of Draggin's and yes, they had to be made for me, they ended up adding 4 inches to the standard leg length

. But the optional knee armour adheres with velcro and I would prefer it in a pocket, so it didn't chafe my knee caps.
Kushitani make a pair of leather denim look jeans
http://www.kushitani.com/kushitani-w...tslexjeans.htm which they claim to be waterproof.
Esquad were making for Ducati, but aren't any longer and whilst Pro Italia were stocking them they don't and now have something called Sartso which claim to have a pocket for armour on the knee, which sounds interesting.
You wouldn't think it would be so hard

. I spoke to Draggin about putting a pocket in and they said it was too hard to gauge where your knee was

one wonders how the manufacturers of leathers manage then.