In order to get the full benefit of Stephen King's Dark Tower series, here is the reading order.
The Stand
The Eyes of the Dragon
The Dark Tower I: The Gunslinger
“The Little Sisters of Eluria”
The Dark Tower II: The Drawing of the Three
The Dark Tower III: The Waste Lands
The Dark Tower IV: Wizard and Glass
‘Salem’s Lot
Hearts in Atlantis
Insomnia
“Everything’s Eventual”
The Dark Tower: The Wind Through the Keyhole
The Dark Tower V: Wolves of the Calla
The Dark Tower VI: Song of Susannah
Black House
The Dark Tower VII: The Dark Tower
https://geekunchained.wordpress.com/...-reading-list/
That URL explains this reading order in more detail.