What you need to do is look at the value for wheel_section and compare it to the value of the last post to see if you need to start a new group
if (have_posts()) {
$last_wheel_section = '';
while(have_posts()) {
the_post();
$this_wheel_section = get_field('wheel_section');
if ($this_wheel_section != $last_wheel_section) {
// new section started
// this will always be true for the first section
}
// other code for each wheel section
// at end of loop set $last_wheel_section to $this_wheel_section
$last_wheel_section = $this_wheel_section
} // end whild have_posts
} // end if have_posts
