With the Pro version you can set the width and height of individual tooltips right from the {tip} tag.

width="200"
height="150"
width="200" height="150"

{tip title="Tooltip Title" content="Tooltip text..." width="200"}width="200"{/tip}
{tip title="Tooltip Title" content="Tooltip text..." height="150"}height="150"{/tip}
{tip title="Tooltip Title" content="Tooltip text..." width="200" height="150"}width="200" height="150"{/tip}