Swedish "tid" is the 'cognate' word to German "zeit"; they correspond to English "tide".
Initial z- in German generally corresponds to t- in the other Germanic languages.
but it gets even cooler!
somehow, swedish (and english) t often shows up in place of german d (or z, like you said), but on the other hand, swedish (and english) d occurs in many places where german has t! just a couple of examples...
:sweden: dotter — :germany: tochter — :uk: daughter
:sweden: dyr — :germany: teuer — :uk: expensive (cognate:
dear)
:sweden: dröm — :germany: Traum — :uk: dream
:sweden: djävul — :germany: Teufel — :uk: devil
:sweden: djup — :germany: tief — :uk: deep
:sweden: djur — :germany: Tier — :uk: animal (cognate:
deer)
:sweden: dricka — :germany: trinken — :uk: drink
and then on the other hand we have the exact
opposite happening, with swedish t and english th showing up when german has a d.
:sweden: tre — :germany: drei — :uk: three
:sweden: betyda — :germany: bedeuten — :uk: signify (this one's doubled up, with t/d each swapped for each other!)
:sweden: tack — :germany: Danke — :uk: thanks
:sweden: Tyskland — :germany: Deutschland — :uk: germany (but cognate
dutch bucks the pattern)
:sweden: tumme — :germany: Daumen — :uk: thumb
:sweden: tänka/tycka — :germany: denken — :uk: think
:sweden: ting — :germany: Ding — :uk: thing
and so on.