I originally ordered the Thunderer and was surprised when I received them because the tread wasn't what I expected... also appeared to be an aggressive tread from the website photos.
After doing some image searches, I found photos of the Petlas and they look like a more aggressive tread to me. The image on the simple tire website isn't a very good representation.
I'll take photos of the Thunderer before I return them and also a photo of the Petlas once I receive them and follow up with a post of both here.
I had the same problem with the tire size search that you did... I found that I had to search for the tire make and model I was looking for, then select the size in the drop down menu to get the 185r14, but they do have them.