After staying for 6 months in the US how long before you can go back to US with your tourist visa?

There is no certain rules on this issue but Immigration officers at every port have full authorization to allow you to enter US or cancel your visa and put you on the plane back to your home country immediately.

If you do not have strong evidence of ties to your job, your family, your home country and you are unable to satisfy the immigration officer at the interview about your situation and reason of long stay on previous visit, etc., you may or may not be allowed to enter US.

My suggestion is if you have a full time job in your country, bring proof of your annual leave issued and approved by your employer. It's the best bet.