help! so Sorry i need another physics fix! centripetal forces?

[miaka]

please, i can't understand my professor, no matter how hard i try and I'm normally very good at physics please show me how you answer this question:
friction between tires and pavement supplies the centripetal acceleration necessary for a car to turn. using the coefficient of
friction for rubber on concrete calculate the maximum speed at which a car can round a turn of radius 30 m. (a) when the road is dry and (b) when is wet. (assumed level road)

r= 30m, coefficient of friction static dry=1 and wet=0.7, if your going to use coefficient of friction kinetic dry=0.7 and wet=0.5

and last how do you derive theta = tan^-1 (v^2/rg), where did this originate? this is a formula for the angle in leaning into curves, still centripetal force.

thanks alot!!! i owe you!