Hi Mark

Not sure about the U.S. , but Immigration to NSW, Australia in the 1800's is online and free.
Frances Coakley's A Manx Notebook , on line , has a listing of Manx people in the U.S. on the 1880 and 1920 Census , and John Teare is not on either. There are about 12 John Teares on 1880 , but none anywhere near his age. How sure are you about the 1863 Immigration ?
Have since found a John William Teare ch 19/6/1850 in Andreas, but he is still on the IOM on the 1871 census.
Also now found his son J W Teare marrying Pearl Willendorf, April 5, 1927, on the 1940 U.S. census he is shown born Minnesota.
I assume you have John's DC 1928 , which only shows born IOM ?
It is going to be difficult to trace him as John Teare is a common Manx name.
One last thing , I could not find him called John William , only his son born 1899.
Having said that, there are a lot of people who visit this site are probably working on your posting right now.
Cheers
David