I did a search for the read specs and they will usually have read speeds for each individual type of disc but this was all I could find. Most DVD Writers or ROMS will only read a pressed/Factory DVD at 8 or 12x and some will read burned DVDs up to 16x and this may be the case with your DVD-ROM. Not positive though. Pretty sketchy specifications.
Type DVD-ROM - 5.25" x 1/2H
Read Speed 48x (CD) / 16x (DVD)
Supported Media Types CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-R, DVD-RW, DVD+RW, DVD+R, DVD+R DL
Media Load Type Tray
Access Time 120 ms
Buffer Size 256 KB
Features Emergency disc eject hole, SMART-X, Auto Balance System (ABS)