what's this?

[WCZ]

any ideas as to what the thing from the wheel is? some kind of lock or something?
purely curious

[addz86]

Something to count the revolutions I’d imagine?

[Reltub]

It looks like a pipe is going from the tyre valve to under the wheel trim, maybe it keeps the tyre pressure constant if there is an issue by using the air tanks for the brakes.

[gianlu]

I know this! As above, it is for tire pressure. Compulsory in Brasil for any heavy vehicle. All wheels are connected to this "central" air system

[agent006]

Yep, CTIS: https://en.wikipedia.org/wiki/Central_tire_inflati...

Often seen over here on trucks that spend time offroad, log haulers etc.