The New York observation wheel is due to go up in 2018 and be the tallest in the world.
In 2018, the world will have a new record-breaking observation wheel. The New York Wheel is set to clock in at 630 feet, making it the tallest observation wheel on the planet.
Source: http://www.iaapa.org/news/funworld/funworld-magazine/new-member-spotlight---march-2017