Originally Posted by 1KChinito
My sister-in-law and brother had to pay a hefty penalty for checking in two 70 lbs bags each person from the U.S. to Asia. They thought that was their limit since they upgraded from Y to C.
They got shafted.

Their limit should have been 70 lbs, as they were flying in C. Doesn't matter whether they purchased it or upgraded; if you have a confirmed C seat, you can use the C checkin counters, C security lanes, etc., and C weight limits should apply.
There's certainly nothing to indicate otherwise on the UA baggage limits page.
Sounds like there's some confusion about these limits among UA TA's. Imagine that.