Kanji reading question
 

I have a question about a certain reading of certain kanji and I noticed mostly it happens with the Chinese reading.
There are kanji that amongst all their readings, they finish with つ, like for example 出　（しゅつ）、立　（りつ）、早　（さつ） ecc... In some of them the tsu is small (sorry didn't know how to write the small kana with the IME), while some of them it is regular tsu.
My question is what the pronunciations are? I mean are they strict like the dictionaries write them or the native speakers change them according on how they sound better to them?

Well, I suppose you already guessed this, but for instance, if you take the word 出発
As an example.. its Shuppatsu. So, as usual, you get the next letter and add a stronger pronounciation to the constonant.

Also, to do a small tsu in IME, I usually type "ttu" to get っつ and then delete the last tsu to get っ

Anyway, does that answer your question?

EDIT: Also, if it has a small tsu reading, you're not going to find that at the end of a word, methinks.

So basically every kanji ending with a つ is treated as っ according to the first letter of the next word. I had the doubt because my dictionary makes a distinction. For example for 十 it puts the reading じゅう、じっ、じゅっ, while for other words puts only the big つ like 立　（りつ）。

(Thanx for the tip on how to use the IME).