Answer
$v = (44~m/s)~\hat{i}$
Work Step by Step
We can convert the speed of the car to units of $m/s$:
$v = (80~km/h)\times (\frac{1000~m}{1~km})\times (\frac{1~h}{3600~s}) = 22~m/s$
The velocity of the tire's center of mass is equal to the velocity of the car.
We can find the velocity of the top of the tire:
$v = 2~v_{com} = (2)(22~m/s) = 44~m/s$
Since the hitchhiker's velocity is $0$, the velocity of the top of the tire relative to the hitchhiker is $(44~m/s-0)$ which is $44~m/s$
We can express this velocity in unit-vector notation:
$v = (44~m/s)~\hat{i}$
