[NormsRevenge]

Some questions .. Im trying to fill my knowledge cap. I haven't read this whole thread yet either, but hope to soon. Thanks in advance if someone can confirm any of the following.

The shuttle is launched with the tires uninflated, if I am not mistaken.

At what point in the re-entry process are they re-inflated, relative to the shuttle's re-entry timeline?

I am not clear if the tires had already been re-inflated when the loss occurred of vehicle.

Is it after falling below so many hundred thousand feet or 8-?

Does this process and its initiation ever vary?

What type of mechanism/mechinery is used and how is the process initiated, etc?

Any pyros involved in opening the wheel doors?

[Cold Heat]

I read somewhere that they have the ability to add nitrogen to the tires to get the pressure up prior to landing.

There are pyros on the latch that holds the wheel assy. in the up position. The door opens by a mechanical linkage which unlocks the door as the wheels begin to drop. No pyro on the door it'self.

[snopercod]

No, the tires are inflated with 235# - 300# (can't remember the exact pressure) of dry nitrogen before they are installed on the orbiter. They are inflated in the "tire lab" and then baked and frozen in environmental chambers to make sure they don't leak at extreme temperatures. Once installed for flight, they are never touched again.

I posted a description of the gear operation earler in this thread, but basically it's hydrauliclly-operated, with pyro backup.