AdWords display image ads - why are some different sizes to what is allowed?

Question

I'm trying to get some ads onto a particular website. I can't/won't name the site but it uses two ads in the body of their articles and the one I'm trying to targets as a placement is 800 x 250 which is a size that cannot be uploaded as an image ad in AdWords.

The code you when see you inspect the ad on the site looks like this:

<script>vu("https://securepubads.g.doubleclick.net/pcs/view?xai\x3dAKAOjsul5PQnDF-EBdR...(it goes on)...")
</script>
<a id="aw0" target="_blank" href="https://googleads.g.doubleclick.net/pcs/click?xai=AKAOjsvidUQJMPo1...(it goes on)...
&amp;sig=xxxxxxxxx&amp;adurl=https://www.xxxxxx.com.au/xxxxxx&amp;nm=8&amp;nx=333&amp;ny=-64&amp;mb=2" 
onfocus="ss('aw0')" onmousedown="st('aw0')" onmouseover="ss('aw0')" onclick="ha('aw0')">
<img src="https://tpc.googlesyndication.com/simgad/1597783....." border="0" 
width="800" height="250" alt="" class="img_ad"></a>

Also, when you view the source of the page, there are tags that look like this:

googletag.defineSlot('/508073XXX/XXX_PremiumNewsTile_800x250',[800,250],
'div-gpt-ad-1500605XXXXXX-0').addService(googletag.pubads());

So my question is, how can I upload an 800 x 250 image ad to AdWords?

OR, should my question be: am I missing something? Is Google the platform used by a third-party provider that allows their own size ads i.e., the site isn't using AdSense?

Answer 1

I have contacted Google AdWords support and the reason I cannot achieve this is that the size is custom because the placement is provided by space provided by an agency using DoubleClick (https://www.doubleclickbygoogle.com/). Thus, even if I could upload an image of the custom size, I could not access the placements on that website without contacting their marketing agency.