The formula for converting an angular velocity expressed in $rad.s^{-1}$ into a linear velocity expressed in $m.s^{-1}$ is given by :

$$v = r \times \omega$$

With :

• $\omega$ angular velocity expressed in $rad.s^{-1}$
• $v$ linear velocity expressed in $m.s^{-1}$
• $r$ radius, expressed in $m$

For example, if a vehicle with wheels of radius 10 cm rotates at 20 rad/s, the vehicle speed is given by :

$$v = r \times \omega = 0.1 \times 20 = 2~ m.s^{-1}$$

You'll find on this page an online converter from angular to linear velocity.