I think you confuse Tradition with tradition.
in the Catholic Church Sacred Tradition and Holy Scripture together make up the Deposit of Faith.
The Sacred Deposit of Faith does not and cannot contain every truth. God is greater than words can ever express, even the words of Sacred Infallible Scripture. God is greater even than His own Deeds in Sacred Tradition. God is infinite and eternal. God cannot be completely described or completely understood by Tradition, Scripture, Magisterium, nor by any finite thing. Therefore, not every truth of Faith is found within the Sacred Deposit of Faith.
Sacred Tradition is “the deeds wrought by God in the history of salvation.” Sacred Tradition includes both the deeds and their meaning. The deeds of God, and especially the deeds of Christ, teach us Christ's Way of holiness, which is partially-revealed in the deeds God wrought in Old Testament times and fully-revealed in Christ's own life of self-giving. The meaning of the deeds includes love, faith, hope, mercy, prayer, self-sacrifice, and more, as Christ put it into practice in the events of His life, His death on the Cross, His Resurrection, and the “final sending of the Spirit of truth” at Pentecost.
Sacred Tradition is not these ideas themselves (of love, faith, hope, mercy, prayer, self-sacrifice, and more), but rather their embodiment in the deeds of God in salvation history, in the life and works of Christ, and in the Church that Christ established. Sacred Tradition is infallible because it is the deeds that God wrought, especially the deeds that God-Incarnate wrought, in the history of salvation. The true meaning of Sacred Tradition is infallible, just as the true meaning of Sacred Scripture is infallible.