Tooltips

There are two ways to assign tooltips to RadRadioButton, namely setting the ToolTipText property of the RadRadioButtonElement, or as in most of the RadControls by using the ToolTipTextNeeded event of RadRadioButton. It is necessary the ShowItemToolTips property to be set to true which is the default value.

Setting the ToolTipText property

this.radRadioButton1.ButtonElement.ToolTipText = "sample tooltip";

Me.radRadioButton1.ButtonElement.ToolTipText = "sample tooltip"

Setting tool tips in the ToolTipTextNeeded event

private void RadRadioButton1_ToolTipTextNeeded(object sender, Telerik.WinControls.ToolTipTextNeededEventArgs e)
{
    e.ToolTipText = "Select a hot drink";
}

Private Sub RadRadioButton1_ToolTipTextNeeded(sender As Object, e As Telerik.WinControls.ToolTipTextNeededEventArgs)
    e.ToolTipText = "Select a hot drink"
End Sub

The ToolTipTextNeeded event has higher priority and overrides the tool tips set in the ToolTipText property.