As for the significance of the tire pressure (it could also have been overpressure) or the apparent contact with the wing by a piece of the external tank, that is all inferred at this point. More from Spaceflight Now's STS-107 mission status page
1404 GMT (9:04 a.m. EST)
We're getting reports from Texas of debris behind the shuttle's plasma trail during reentery.1401 GMT (9:01 a.m. EST)
Columbia is out of communications with flight controllers in Houston. Now 15 minutes from landing time.1359 GMT (8:59 a.m. EST)
At an altitude of 40 miles, shuttle Columbia has entered Texas.1357 GMT (8:57 a.m. EST)
The shuttle is now 43 miles over New Mexico. Columbia is now reversing its bank to the left to further reduce speed.1356 GMT (8:56 a.m. EST)
Columbia's speed is now about 15,000 miles per hour as it streaks over northern Arizona.1355 GMT (8:55 a.m. EST)
The shuttle is now soaring over the southern portion of Nevada. Columbia set for touchdown at Kennedy Space Center in Florida in about 20 minutes.SATURDAY, FEBRUARY 1, 2003
1353 GMT (8:53 a.m. EST)
Columbia is now crossing the California coastline.SATURDAY, FEBRUARY 1, 2003
1351 GMT (8:51 a.m. EST)
Altitude 47 miles. Speed 16,400 miles per hour.1349 GMT (8:49 a.m. EST)
Columbia is beginning the first in a series of banks to scrub off speed as it plunges into the atmosphere. These turns basically remove the energy Columbia built up during launch. This first bank is to the right.