Right offhand I'd say no. It looks like the RPM is 200, and I'm assuming the torque is 6.5 kg-cm(?). So available torque at 1:1 ratio on a 25 cm diameter tire would be about half that, or 3.25 kg-cm. To get to 6 km/hr with the same tire you would need about 3:1 speed increase, which would reduce the torque to about 1.1 kg-cm. With all the other considerations (rolling resistance, elevation increases in common roads, even flat ones) I don't see it working.
What is important is the power rating of the motor. As @CWatters calculated, there is a 13 W output (it is actually 9.4 W, since the rated RPM is 140 rpm and not 200 rpm). This is a replacement motor for a ride-on of this kind and it is rated at 170 W; so a lot more. And it is cheaper than yours!