preflop standard question vs. maniac

[kamelion44]

Game is Party Poker SH $10-20. I have perfect position on maniac, who is seated two to my right. Sandwiched between us is a TAG whose stats are 25/17 through 1k hands. My question is, what are your guys' standards for capping or at least calling an isolation raise from the TAG? The exact situation was I had 55, the maniac raises, which he does almost every hand since his stats were 86/64 through 2k hands, and the TAG 3-bets...(results: he shows down 44 and wins UI after I fold PF). I think 55 is still too light here, but what are your exact standards here?

Thanks