In the Wordpress Theme Midway Responsive I want to increase the tour columns on the tour page.

The key to doing this is on the page
wp-content/themes/midway/template-tours.php on line 115 we have the code.

if($counter==$row_limit) {
                        $counter=0;
                         echo '< div class="clear"></ div>';
                    }

If you ADD above

$row_limit = 5;  that will enable you to have a row of five ( with some CSS tweaking )  
The value for $row_limit is not set in the database but on line 11 of this page.

$row_limit=$layout!='left' && $layout!='right' ? 4 : 3;
$row_class=$row_limit==4 ? 'three' : 'four';
changing the code here means you'll have to make a few more CSS adjustments.  For me the Hack works fine, so I'll it as be.

Remember if your making these changes it makes sense to do so in a Child theme.