Bad columns formatting by the tr command

I have a file like this AAA:111111:FIRSTLINE BBBBBBB:22222222222:SECONDLINE CCC:33333333333333333333:THIRD LINE And I wanted to change each ":" by a tab. For that, I used the tr command tr ":" "\t" But I got this ABC 12345 FIRSTLINE DEFGH 1112232 SECONDLINE IJK 77623786487261 THIRD LINE I want to make the words in the third column all starting in the same place, but it seems that when a word in the previous column is too long, the word from the next column moves much foward than I want. Is there a quick way of solving this? Thanks.