Using larger icons (30x30) in listviews?

Using larger icons (30x30) in listviews?

Hello, I've found those icons I'd like to use in listviews.
The icons have got a size of 30x30px.

If I use the class "ui-li-icon" for the images, they gonna be resized to 16x16.
  1. <ul data-role="listview" data-inset="true" data-theme="b" data-dividertheme="b">
  2.    <li data-role="list-divider">Menu</li>
  3.    <li><a href="/link1"/><img src="/images/icons/icon-mail.png" class="ui-li-icon" alt="" />Link1</a></li>
  4. </ul>

If I don't use that class, the item will have a double height. How can I fix that problem?