Use them as point-defense against armored assaults, that is, do not use them offensively; use them in defensive fire against armor when it assaults. The 57mm is capable even against the side armor of Panthers, as that's what you'll be hitting in defensive fire.
Tigers are bit more of a problem, however, if your paras are dug-in and
GtG (Gone-to-Ground) you'll be tough to remove. You can use mortars to smoke them to keep them moving, reducing their
ROF. When they do come at you in an assault, they'll have to be supported and any Tiger worth its salt will not go in alone against dug-in paras. You hit it enough in assault, it will eventually run away. Might want to consider some engineer/pioneers for some close-assault
AT power (if it's an option). Your arty can fire directly and if nearby can participate in defensive fire if within the 8" bubble.
Your air-support has the potential to knock out Tigers early on in the engagement, but once they close with 16", as others have noted, your air-support will have to look for other targets of opportunity. The good counter to them is running Tank Destroyers, again if you have the option for them.