The Russian is in the past tense, but it's usually translated into English with the present tense. Because English normally uses the adjective tired, while Russian normally uses the verb уста́ть ('to get tired').
While both English and Russian allow wording it differently (e.g. if you wanted to show the grammar of 'я уста́л(а)' in English, you would use 'I got tired'; and to show the grammar of 'I'm tired' in Russian, you could use 'я уста́вший/уста́вшая'), these variants sound less natural.
so is there a different form that doesn't imply you are still tired?
In standard Russian, you could try specifying the time when you were tired:
- Я уста́л(а) вчера́. 'I was tired yesterday.'
- У́тром я о́чень уста́л(а). 'I was very tired in the morning.'
If the context specifies some time in the past, it won't imply that you're tired now.
(In my own speech, I would use the plusquamperfect tense for this, but this is not standard Russian.)