Why is the 't' pronounced like 'ch' sometimes or even like "t+sh"? Do the English phonotactics allow for a word to start with "ch+r" ('ch' as in 'chair', not as in 'Christmas')?
This doesn't appear to be true for all languages. The 't' (three) in the Croatian word 'tri' is pronounced quite differently from the 't' in the English word 'tree', even though they are usually pronounced the same. Also, the word for 'black' in the Kaikavian dialect of Croatian is 'črn' ('č' representing a 'ch' sound), while the word for 'thorn' is 'trn', and those are pronounced quite differently.