There are suggestions just a few hundred are left for the trip along the M4 this weekend.
The game is a 3:00pm kick off on Saturday.
Contact the ticket office on 0845 345 1400 to secure tickets before they sell out.
Source: FOOTYMAD
Bluebirds heading for Reading in numbers
Most of the 4,000 tickets for City's trip to Reading on Saturday have been snapped up.
