I have two questions about them- first what do you call the kind of rims where the rim strip lays right over the nipples, rather than the nipples being down in little wells (like on steel rims, but a lot of them are aluminum now). Are those what I`ve heard refered to as "single wall rims"?

Second, they aren`t supposed to be tensioned up like a "nice" rim, are they? When they show up, they almost invariably have bad wobbles and zero tension. As long as the nipples aren`t frozen or bottomed out, I can usually get them fairly true, and I normally tension them to the point where they just start to "ping" when plucked, but if you squeeze a pair of them, the whole wheel just bends towards the side you`re squeezing. I`m afraid to go any tighter- should I be afraid of that?

Before you tell me to buy "real" wheels, I want to explain that I volunteer sometimes at a shop that fixes bikes for free or for a very small donation and most of our customers are either homeless or otherwise don`t have the money for better stuff. Besides that, I end up working on a lot of cheapo bikes from family members or neighbors and sometimes I even have one myself. But just because it`s chinzy doesn`t mean it shouldn`t be in as good as possible condition, right? Any related advice appreciated.