I have some code im playing with that is a tick and execute state machine' os (i guess what you call it)
and all my integers were int types, the code compiled to 552 bytes of flash.
I changed all the integers to unsigned 8 bit integers (uint8_t) and the program size dropped to 416 bytes!
And this was with only ten integers, saved 136 bytes. Optimization set to [-Os]
I knew there were other number types, floats and what not. It did not occur to me to define something lower than an int' integer.
Probably also got 8bit, 255 max stuck in my head because of learning the timers recently, none of my numbers go above 255! ;p. green...