Use AppCompatRadioButton instead of RadioButton.
<android.support.v7.widget.AppCompatRadioButton
android:id="@+id/rb"
app:buttonTint="@color/colorAccent"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
To change the color programatically do this:
ColorStateList colorStateList = new ColorStateList(
new int[][]{
new int[]{android.R.attr.state_enabled} //enabled
},
new int[] {getResources().getColor(R.color.colorPrimary) }
);
AppCompatRadioButton radioButton = (AppCompatRadioButton) findViewById(R.id.rb);
radioButton.setSupportButtonTintList(colorStateList);