Matteo,
You can always force the size via CSS. You can add this to the Custom CSS box that’s in the styling tab of the theme options page:
.woocommerce div.product div.images img,
.woocommerce #content div.product div.images img,
.woocommerce-page div.product div.images img,
.woocommerce-page #content div.product div.images img {
width: auto;
}
With all the stylesheets combined on the site, it’s a bit tricky to determine exactly what’s happening here. The default layout of a WooCommerce product is to have the the images floated to the left and take up 45% of the top portion of the page.
The default WooCommerce CSS has the images in the image section set at 100% width so if the width of that section is changed to be 100% instead of 45% it’ll make them really big. Does that make sense?
Regardless, you can set the width to be the actual dimensions of the image with the snippet above.
Let me know if you run into any trouble there.
Thanks,
Bill