Nathan and his family are touring Chicago. They want to visit the Sears Tower, hang out at Navy Pier, and shop on Michigan Avenue before their dinner reservations at 4:40pm. They plan to spend 45 mins at the Sears Tower, 2 hours and 10 mins at Navy Pier, and 1 hour and 45 mins shopping. What is the latest time Nathan's family can start their tour of Chicago and still make it to dinner on a time?