I believe there are two common mistakes (that I can think of) that occur when a player tightens up. Playing tighter is normally not the direct problem but can sometimes
lead indirectly to other problems. The first is becoming too
passive. A lot of players associate tightness with passivity which will usually result in less earnings in my opinion. The other mistake is exactly the opposite. You're seeing less hands so you have developed the mentality that you need to earn more from the few hands you are playing, in respect, twice as much with a
vpip of 13 compared to a
vpip of 26 since you're seeing half the hands. This results in over aggressiveness and overcomittment to hands. You're trying to force your good cards down the throat of your other players even when they're not the best hand, only the best whole cards.
With this being said, I think the second mistake might be what you're doing. The reason i believe this is because you said it helps in
SNG's. When you're playing
tight in
SNG's most of the hands you enter will be when the blinds get high and you're usually committing your
stack preflop. Odds are better for you this way so you will naturally win more.
Honestly, I would suggest loosening up in
late position for your ring play. Try to get your
vpip around the low 20's. While you're not playing the premiums anymore (I suggest
suited connectors, gappers, etc) you're also frequently playing more postflop
action and the tendency to feel like you have to win has been slightly alleviated. I had this same problem and this solution has helped me tremendously. Added bonuses include looser
table image ("this guy is limping or even raising!!!
suited connectors or gappers in late???") and will get more of those premium hands payed off.