I would recommend getting the music tapes in practice mode. The achievement will still count and you won't need to worry about the timer.

Golden Bay Burbs map
It's on top of this building, if you drive closer to the building there is a jump pad that will launch you to the collectible.

Golden Bay Downtown Map
By a gas station, just boost off the ramp to get it.

La Oasis Airfield map
On top of the airplane.

Isla Honu Tourist Trap map
On top of the building you spawn near. Boost off the ramp to get it.