NVDA - Mar.'18 Exp. Put Vertical Credit Spread

Trade details:
175/160 Put Vertical Credit Spread @ $2.93
Prob. of Max Profit = 72.17%
Prob. of Max Loss = 14.05%
Break-even @ $172.07
84 D.T.E.

Trade plan:
Entry by oversold + support/resistance analysis
Expecting a response up or down from $191.20 support level test, probably during next week or the early in Jan.
Expecting older support level to hold strong at $170 until Mar.'18 expiration, otherwise adjust to minimize loss if price tests and consolidates at break-even level.
RISKS: Break-even within the at-the-money straddle expected move by expiration; bid/ask spreads ~$0.40 on entry; earnings announcement before expiration.
Using longer duration for some more premium + the opportunity to adjust spread if trade goes very wrong early on.
Expecting spread to expire worthless but will take early profit + place new trade with same bias around earnings if IV swells premium up enough.