In English, when /t/ is followed by /r/, it becomes more retroflex, meaning the tip of the tongue curls towards the roof of the mouth. The combination of a retroflex /t/ and /r/ sounds a lot like /t?r/ ("chr"), but not quite.
Noemon: There isn't any difference between "ch" and "tch"; or rather, if you think there's a difference, that doesn't seem to capture it. The IPA symbol for the "ch" sound is actually two symbols (sometimes written as a ligature): /t?/. It's just the symbol for "t" plus the one for "sh." So if "ch" is /t?/, then "tch" is /tt?/, which probably isn't what you meant.
Porter: There probably isn't any difference between your pronunciations of "where," "wear," and "ware." Presumably you also pronounce "whale" and "wail" the same, and "marry," "merry," and "Mary" the same.