The answer depends on your bone structure. Do you have a small, medium or large bone structure. Easiest way to tell is to wrap your hand around the opposite wrist bone and see if your thumb and middle finger can touch, or over lap.
If they can overlap the length of your finger nail or more than you have a small bone structure, if they just barely touch and don't overlap much then you have a medium bone struicture and if they can't touch then you have a large bone structure.
I know this is simplistic but its a pretty good gauge.
Now if you have a small bone structure your ideal racing weight will probably be at a BMI of 19.0 to 20.0, if you have a medium bone structure you will probably be ideal at a BMI of 20.0 to 21.0 and if you have a large bone structure you will be probably be ideal at about 21.0 to 22.0 for BMI.
If you exactly 5'6" (no shoes) then here is the weights for the following BMI's
BMI of 19.0 = 118 lbs
BMI of 20.0 = 124 lbs
BMI of 21.0 = 130 lbs
BMI of 22.0 = 136 lbs