80 minutes CDRs can even be "overburned", meaning that you can ask your burning software tool to go drive the writer's head beyond the theoretical limit of the CDR's writable zone. Most 80 minutes disks will allow you to burn up to 82, 83 minutes of music. Not all software tools have this feature, but Nero does.
There also exist 90 minutes disk. Some of them are directly recognised as such by Nero, meaning that Nero will allow you to select up to 90 minutes of music without creating an error. But some 90 minutes CDRs are recognised by Nero as 80 minutes disks, and you must then ask Nero to overburn the CD if you want to put more than 80 minutes of music on it. Just tell Nero that you want to overburn the CD up to 90 minutes, and you won't have troubles with it.
Note, however, that the overburning of a 80 minute CDR or the burning of 90 minute CD is only possible with recent hardware. Old burners won't allow you to exceed 80 minutes. Note also that CDs exceeding 80 minutes won't play in some standard CD players.
Good luck.