Set the Jetpack Tiled Gallery Width

There is a way to force the Jetpack Tiled Gallery with: it’s actually a filter to a function available in Jetpack.

Look for “$tiled_gallery_content_width” in the “tiled-gallery.php” module and you’ll notice that the default width is 500px.

https://github.com/Automattic/jetpack/blob/master/modules/tiled-gallery/tiled-gallery.php

Here’s how to change the tiled gallery size using a filter:

add_filter( 'tiled_gallery_content_width', 'personal_full_tiled_gallery_width' );
function personal_full_tiled_gallery_width( $width ) {
    $width = 1140;
    return $width;
}

Alternate way: redefine the global variable “$content_width” in the template.

See example here: https://developer.wordpress.com/themes/content-width/

References

http://hookr.io/filters/tiled_gallery_content_width/
http://www.functionsphp.com/jetpack-tiled-gallery-width/
http://wpsites.net/web-design/change-tiled-gallery-content-width-for-jetpacks-tiled-galleries/