recommened throttle boost and tire size adjustments?

[Tava]

So, I am running the canned 89 tune and am so far very happy. how much is a safe amount to bump up the throttle boost??

also, tire size?? does the computer not already know this if I am running factory tires and rims??? no need to mess with this setting, right??

[STUNNAH]

20% on the throtte...No need for tire adj...