Thiele did a lot of research to understand the dating of the Kings of Israel. I disagree with him occasionally for theological reasons. He would make changes if doing the book today, simply because more data is dug up all the time, or becomes available more generally (especially because of the internet). But what he published in 1982 was a summary of all that research into understanding the dates given in the Hebrew Bible for the kings of Israel and Judea.
To simplify, not all cultures use the same systems of dating. Did a king co-reign with his father? Because one source might say X occurred in his 3rd year, another source might call it his 11th year - talking about the same event, same year, but one source counting from his sole reign, the other from when he first began to co-reign. Howabout, is this year 1 or zero of King X? Do you use an inclusive count or an exclusive count. I'll give one example. To an American, a week is 7 days, 2 weeks is 14 days, 3 is 21 days, etc. To the Hispanic, the week is 8 days, 2 weeks is 15 days, 3 weeks is 22 days. The American way is exclusive, the Hispanic is inclusive. They make as much sense, they're just different. Not knowing the difference can mess one up: Julius Caesar got his calendar from foreigners (Egypt & Greece). They said to have a leap year every four years (they were talking exclusive count). So Caesar told his fellow Latins to have leap year every four years - but they just assumed it was their inclusive count. That meant it was every three years in the exclusive method. So from something like about 15 BC to about AD 5 (I forget the exact dates, just giving it from memory, but included the whole time frame when Jesus might have been born) they had no leap years so they could get the calendar back in sync.
Thiele goes through the Biblical and archaeological evidence to find out which kings (or at least their recorders) used what system of dating. It turns out that what look like errors in dating of the kings (say, II Kings says he was king 17 years, II Chronicles says 18) aren't errors. The dates from the Bible work out very nicely if you understand the multiple systems in use, and fit nicely with the secular dates as well.
There are a couple places he chooses to decide there is an error in our current Bibles, either because of copyists errors in the manuscripts we've chosen to use, or, because we didn't and maybe still don't know about another system in use. ( )

Sometimes interpreting the Bible is -- to put it delicately -- a tricky matter. A case in point: The chronology of the Kings of Israel and Judah found in the books of 1-2 Kings. There are, in effect, two schemes in use, the length-of-reign scheme and the synchronism scheme. The first says that King X reigned for thus-and-so-many years. The second says that King X came to the throne in this-that-or-the-other year of King Y of Israel or Judah.

The problem is, sometimes this doesn't work. To make up an example, if King Omri comes to the throne in the year five of Jehoshaphat and reigns seven years, and Omri's son Ahab comes to the throne in the year twenty of Jehoshaphat, then either somebody has a time machine or we have a problem. It is simply not possible to reconcile the length-of-reign and synchronism schemes while assuming the same calendar system is in use throughout. These must also, of course, be reconciled with the handful of fixed dates we know from other sources (such as the year in which the city of Samaria was destroyed by the Assyrians).

The usual response has been to pick one scheme or the other as fully correct and change the other as needed. William F. Albright, for instance, used the synchronisms to create his widely-accepted chronology.

Edwin R. Thiele didn't accept that. Rather than accept errors in the Biblical text, he assumed, first, that the form of the calendar used was changed on a few occasions, and second, that various kings took on their sons as co-regents, and that none of these co-regencies is correctly recorded in the Biblical tradition. The result takes those "mysterious numbers" and cleans them up almost completely. There was one instance, which Thiele openly admits to, where he could not come up with a trick to make it work. But every other number he successfully reconciled either by calendar trick or co-regency.

It is a tour de force. The question is, is it correct?

Different scholars differ. To me, it seems that Thiele bends so far over backward to make everything work that he simply goes too far. Several of his proposals, such as those about co-regencies, make very good sense; they might be worth adopting even without the chronological problems. But too many of his proposals have no real justification except to correct a number which might have been miscopied or misunderstood in the centuries of manuscript transmission. Thiele's ideas deserve to be listened to. But I'd rather have seen the work done with an eye to history than an eye to theology. ( )