I've mentioned before that LaBella tapes are a 40-98 roundwound set underneath the tape. Richard Cocco, president of LaBella, told me that himself. And the next time one of my sets lost intonation, I cut them and measured with my digital calipers before throwing them away, and they were exactly that size.
D'addario publishes a
string tension chart (.pdf) that explains the formula for string tension -- see page 4. Weight per unit of length determines the tension. The thin layer of nylon tape on a tapewound weighs almost nothing, the LaBella tapes have no more tension than a typical extra-light roundwound set.
Somebody sent me a link awhile back to a TB thread where some boob insisted the LaBella tapes had torn the top off his ABG. Either he damaged the top some other way and is mistakenly blaming the strings, or he's just a damned liar.
