Hence where it’s confused with Bartlett. If there are very few on the tree and I mean 10 or less the pears can be bigger kind of like a Bartlett but rougher but very large. Here is an example note the 3 larger pears look less red. I think Bartlett is a stretch but they don’t look like ayers but they are. That is more rare to see those larger pears than you would think. Side by side you can see those look like a different type of pear but they are not. The shaded side of the pear won’t be red at all. One not shaded at all in full sun will be all red.
Here is another link showing ayers once again I thought was red blushing Bartlett which I’m still laughing about Here comes the 2018 apple & pear harvest!