Newbie welder question.

I sold welding equipment for 30 years and I always recommend to use on flux cored wire the next bigger tip. Flux cored wire doesn't run true to size and can cause feed problems if you run a .030 tip with .030 wire. I have also used the next side up tip on hard wire ( using gas ). The .023 does work better on thinner material because the gas will help cool the material