uploaded image file attribute changes to www:wheel ?

[Kernow]

Anyone aware what would cause attribute changes www:testsite and www:wheel to uploaded images
and able to enlighten me on what is used as the uploader allowing permission/owner changes

ls -la images/virtuemart/product_images/resized
total 14
drwxrwxrwx   2 testsite  testsite   512 Jul 24 09:24 .
drwxrwxrwx  13 testsite  testsite   512 Jul 24 09:22 ..
-rw-r--r--   1 www    testsite  4247 Jul 24 09:22 0827_90x90.jpg
-rw-r--r--   1 www    wheel  4073 Jul 24 09:24 sm-084.jpg

[Kernow]

Still really puzzled why file attributes are changing for files uploaded within Virtuemart
why would it change to www:wheel 
and whats being used to change/write the attribute changes
to a group higher than Joomla install uses itself

as per >> -rw-r--r--   1 www    wheel   26239 Jul 24 09:22 0827.jpg

ls -la public_html/images/virtuemart/product_images
total 2446
drwxrwxrwx  13 testsite  testsite    2560 Jul 24 11:34 .
drwxr-xr-x   7 testsite  testsite     512 Jul 24 09:05 ..
-rw-r--r--   1 testsite  testsite  132973 Jul 18 15:59 005.jpg
-rw-r--r--   1 testsite  testsite   11447 Jul 18 14:28 024.jpg
-rw-r--r--   1 testsite  testsite   17448 Jul 18 14:29 026.jpg
-rw-r--r--   1 www    wheel   26239 Jul 24 09:22 0827.jpg
-rw-r--r--   1 testsite  testsite  198315 Jul 18 13:55 120.jpg
-rw-r--r--   1 testsite  testsite  628065 Jul 18 14:02 24w_streetlight.jpg