I would like to know the name and the usefulness of this piece that covers the top of the tire of some planes, such as some Cessnas.
1$\begingroup$ Related: What is “spatted undercarriage”? $\endgroup$– PerlDuckMar 22, 2020 at 12:38
$\begingroup$ In general, a "fairing" is something you add on a "thing" so as to make it smoother to go through the air. You could have a fairing for an antenna, a fairing for some sort of instrument, and so on. I suppose the things in your picture are called "wheel fairings" ! $\endgroup$– FattieMar 22, 2020 at 16:41
Those are called speed fairings.
They make the shape over the tire more aerodynamic and reduce drag, thus increasing airspeed and fuel efficiency.
This is a page in a Cessna 172R information manual that comments on the differences in performance when they are installed.
13$\begingroup$ Alternate name: "Wheel Pants." $\endgroup$ Mar 21, 2020 at 0:28
2$\begingroup$ I have never heard/seen them being called "speed fairings" before. $\endgroup$– jamesqfMar 21, 2020 at 4:06
9$\begingroup$ In general, any body part of a vehicle whose sole purpose is to reduce drag by streamlining pointy bits is called a "fairing". $\endgroup$ Mar 21, 2020 at 20:09
3$\begingroup$ In the UK they are often called 'wheel spats' $\endgroup$ Mar 22, 2020 at 10:16
"Wheel pants" is a common term for these wheel fairings, at least in US usage, which serve to reduce drag. They have also been called "spats", though that term has traditionally been reserved for something much larger, at least in US usage.
How can drag induced by the landing gear be reduced?? -- see all answers
What is "spatted undercarriage"? -- see all answers
Some people call them gear socks, but yeah, if you had a problem with them and needed to notify ATC, you would probably call them wheel fairings.