How about something like...
(for each tile)
tile.scaling=tile.width/64 - ie to make all the widths 64
tile.newwidth=tile.width/tile.scaling
tile.newheight=tile.height/tile.scaling
It's up to you whether you think you would need to use floats for the division - if you are using sizes in powers of 2 (ie 32,64,128,256 etc) then integers should be fine.
(for each tile)
tile.scaling=tile.width/64 - ie to make all the widths 64
tile.newwidth=tile.width/tile.scaling
tile.newheight=tile.height/tile.scaling
It's up to you whether you think you would need to use floats for the division - if you are using sizes in powers of 2 (ie 32,64,128,256 etc) then integers should be fine.