Maybe the people who run this game need to update their published information. I don't sit and pour over these forums for information that should be published in plain sight. As I said, I pay money to play this game, I think its not asking too much for the rules to be clear and available. What follows is what is published.
From the FAQs:
What are Tiers?
A tier is your golf classification at World Golf Tour. Based on the scores you shoot in a 9-hole or 18-hole Ranked Stroke Play rounds or Stroke Play Tournament round, you will be placed into a tier.
Advancing to the next Tier requires a qualifying Average Score AND a minimum amount of completed stroke play games, which will take a little more time but will help players reach the Levels necessary to unlock upgraded equipment that is helpful to compete at higher Tiers.
What is Stroke Play?
A stroke play (skill contest) tournament is a tournament where the person with the lowest score wins. Each shot that a player takes during the round is counted and it totaled up at the end. All of the players who have entered the tournament will be competing against the players in their same tier.
What is a Ranked Round?
A ranked round is a stroke play round that will count towards calculating your tier. If you are playing a ranked round and you decide to quit or you lose your internet connection your current game will be saved automatically. You will be prompted to continue your game or quit it the next time you begin a round.
From the Forums:
What average do you need to Tier up, how many rounds do you need?
When Hack average is equal or less than 100.00 you move to Amateur
When Amateur average is equal or less than 80.00 you move to Pro
When Pro average is equal or less than 72.00 you move to Tour Pro
When Tour Pro average is equal or less than 67.00 you move to Master
When Master average is equal or less than 63.00 you move to Tour Master
When Tour Master average is equal or less than 61.00 you move to Legend
When Legend average is equal or less than 60.00 you move to Tour Legend
When Tour Legend average is equal to or less than 59.00 you move to Champion.
But
Unless you win Ready Go Tourneys you need a certain minimum number of rounds played before you can move up to a higher Tier. This is commonly known as “saturation.” Once saturation is reached WGT calculates your average based on the best rounds you have played in your current Tier. Both the minimum to get to saturation and how many rounds your average is based on is:
5 ranked rounds as Hack before reaching Amateur
10 ranked rounds as Amateur before reaching Pro
20 ranked rounds as Pro before reaching Tour Pro
25 ranked rounds as Tour Pro before reaching Master
40 ranked rounds as Master before reaching Tour Master
50 ranked rounds as Tour Master before reaching Legend
500 ranked rounds as Legend before reaching Tour Legend
200 rounds as Tour Legend before reaching Champion