Indeed "tu" is correct, grammatically. But in this case - in everyday language - italians very often use "te" even though it's wrong. Don't ask me why we do this. Notice that this is very colloquial. Obviously you can always correctly say "io e tu". it's colloquial / slang
The Treccani has another opinion. "io e tu" is - nowadays - not correct "tu e/ed io" or "io e te" instead are correct.
it's debated. Here it is the complete story:
Aha, thank you! It's the same thing as when in English people say 'she took Steve and I to the station' or 'me and Steve went to the pub' - grammatically painful, but common.
Unfortunately true and on the increase. Even the "Times" is not immune to this, with one of its (very well known) contributors recently writing "me and my sister went on holiday".
Andare is 'to go', andare a piedi is 'to go on foot' or walk, camminare is 'to walk'. I use this dictionary constantly http://www.wordreference.com/iten/andare%20a%20piedi
this should surely be 'io e tu camminiamo' - so who's the teacher here ?
Not, it has not to be surely "io e tu"!
"io e tu" nowadays isn't used anymore. "tu e io" or "tu ed io" are correct and also in the modern language "io e te", but the use of "io e tu" sounds odd.
"Io" is a subject pronoun and "te" is an object pronoun