Using Filters to append a class to a template container

Ok so I'm not very strong in php and java, I'm learning tho. Now I'm working with genesis using epik if that matters. Having no luck but trying to write a filter to add a class to a specific div on a template in functions.php

I've widened my site but I do not want the entire Blog section (blog home, categories and single post) to be as wide so I can use the native programming, plus learn how to write this stuff.

right now I'm controlling the width via my style sheet

    .page-id-89 .site-inner .wrap {
    padding: 0 5% 0;
}

How can I write this as a filter and hook it to the '.site-inner .wrap' in the above mentioned sections of the site?

so basically the function looks for '.site-inner .wrap' and appends a class (say .squeeze) with my padding to it on those post types

I appreciate any help as I learn my way through this! Have a great weekend