What does it mean

[TRE]

When hubs are reconed on a wheel

 

[Rocket car]

When hubs are reconed on a wheel

I believe that is on-the inside of the wheel, where the axle pokes through. It is re-shaped for less rub on the body.

 

[tmeyer]

The end of the inner hub on the inside of the wheel is reshaped to have less of a contact area to reduce friction when the wheel hub touches the body.

 

[bracketracer]

I'm going to say that it applies to the outer hub as well. The outer step gets cut down and the outer hub formed to a flat cone shape. Stock outer hub on left, modded outer hub on right. See the difference?