Are you going to move everything inside the 30 to the 55 also?? I have a suggestion for you but it includes taking the substrate from the old tank and using it in the new to help aviod a full cycle of the aquarium.
You'll need atleast 2 - 5 gallon buckets for my method. I've never had a problem doing it this way and never noticed any major cycling after doing so. I wanted to switch the place of two tanks and obviously doin so full is not an option so....
I drained one tank to the point where it had only a couple inches of water left in it and the substrate. Get some help for moving it to the kitchen or any other table. I kept 2-5 gallon buckets of old water, one bucket had the fish in it.
I did the same with the other tank and instead of placing the tank out of the way I put it in it's new place. I then added the old water from the bucket that had no fish in it and used that bucket to treat water and fill the tank to the point I was comfortable putting the fish back into it. Next I put the fish in and also the water they had in their bucket. From there on out it was just a matter of filling the tank back up with treated water. Between the filter, the decor and the sand I didnt have much of a bacterial loss. Make sure to keep everything you're going to take from the old tank and put into the new tank WET. As long as everything is wet you should be ok for a couple hours before beneficial bacteria start to die off.
oh yeah, and after i was done with the first tank I still had to move the second off the kitchen table and into it's new place and fill it up too!! SWMBO wasn't happy about eating in the living room LOLOLOL
(SWMBO = she who must be obeyed )
p.s. this is just my limited experience so take it as you may. this is by no means the best way to do it. this is just how I managed to get it done. while i may get flamed for moving an aquarium with water in it, it was very little, just enough to keep the substrate submerged. and as a side note i will be moving a 40 gal breeder from one room to another and unless someone else has a better method i'll be doing the exact same thing in about a week.