During a very quick stop, a car decelerates at $7\mathrm{.}20$ m$/$s$2.$

$($a$)$

What is the angular acceleration $($in rad$/$s$2)$ of its $0\mathrm{.}260$ m radius tires, assuming they do not slip on the pavement? $($Indicate the direction with the sign of your answer. Assume the tires initially rotated in the positive direction.$)$