It is allowed to read Quran with out Wudhu as far as you do not touch the writing of the Quranic text. Touching the Quranic text with out Wudhu is not permissible at all, but touching the Quran is allowed as far as you do not touch the Quranic text.
It is always recommended to be with Wudhu, especially when reading Quran.
Wassalam.