Ok I am looking to add a transfer switch so I can run my generator when the power is out. I have always been told that my transfer switch needs to be rated higher then my generator's output. The problem is my generator has two output rating stated. In other words, a constance rating of 5,550 kw with a start up 8,550 kw.

Therefore will a transfer switch of 7,500kw be to small and I should be looking at a 10,000kw panel?

This is the kind of thing that requires a electrician. Last year several people were electrocuted here because everyone was trying to run generators.
I can tell you the safest way to use a generator is with drop cords running straight to the device to be used.

Matt, from what I have been hearing running a Gentran switch is safer for Lineman and home owners. The electrician I am dealing wanted me to purchase a 7,500 kw 6 circuit Gentran switch but I have been able to reach him for a couple of days. I guess I'll purchase the 10,000 kw 10 circuit panel just to be safe.

Have you looked at interlock plates? Look at some of the old threads starting with https://www.askmehelpdesk.com/electr...elp-48227.html If you can find an interlock plate that fits your breaker box, they are much cheaper and allows you to select any circuits in the house up to the capacity of the generator. Much easier instaltion too. UL approved.