You should look at here:
ROOT/templates/<yourjoomlatemplate>/html/com_virtuemart/productdetails/default.php
(default.php or flexv2.php which ever you chose from VM Configuration for "product details page" layout.)
You can change this line:
<div class="floatleft width20 FlexibleShareItemLeft">
to this:
<div class="floatleft width30 FlexibleShareItemLeft">
(or even larger if width20 -> width30 doesn't enough...)
Regards.
Forum Support.