Tread: The visible outer part of the tyre that is in contact with the tarmac.
Track conditions: This word signifies a lot of track related data like surface temperature, asphalt roughness, grip levels provided by the asphalt etc.
Steering lock: The amount of steering input (rotation) in degrees given by the driver to negotiate a corner.
Sandbagging: This is a term now often used in the new-for-2007 Qualifying sessions. This generally means that a driver is driving well below his limit (which means he is going very slow) for tactical reasons.
Tyre blanket: This is an electrical cover sort of thing that is put on a tyre to bring it upto and maintain it at the correct operating temperature. This obviously makes it clear that F1 tyres wont work at room temperatures.