Answer
$\alpha=8.71rad/s^2$
Work Step by Step
We have $v_0=0, v=22m/s$ and $t=9s$. The tire's linear acceleration is $$a=\frac{v-v_0}{t}=2.44m/s^2$$
In rolling motion, $a=a_T=r\alpha$. We know the radius of the tire $r=0.28m$. Therefore, $$\alpha=\frac{a}{r}=8.71rad/s^2$$
