Originally Posted by
Jiangsu
I'm currently UA 1K, that's *G for AC flight as well.
I am going to travel from YYZ to PVG with a
oversized luggage, its
linear cm is about 185CM (88+24+73, maybe it's overweighted as well) ,but the luggage restriction of AC for international flight is only
158. Clearly, I need to pay $100 for the oversized luggage.
What's the best option for me now? Is it more economical to buy a small luggage bag instead of paying the
$100 luggage allowance fee? How can I deal with this issue?

If you can buy a smaller luggage bag for under $100 then presumably that option is more economical. Otherwise well, if you don't need the extra piece of luggage for the future, pay the fee.
The options you mentioned are pretty much your only ones... good luck.