I agree, JW tires are very sketchy on asphalt. You best not be doing any spirited riding.
AND,..
Taking street tires off road is a lot safer and easier than taking off road tires on the pavement.
You just need to go slower and be careful in the dirt with a street tire.
I had a 1982 Honda XR200R that wasn't street legal.
All it needed to be street legal was to install a horn and replace the dirt tires with trail tires.
Dirt tires on an ebike is stupid.
Ebikes simply don't have enough power to take advantage of huge knobbie tires.
I used to shoot 30 foot rooster tails with my dirt bike.
My ebike gets stuck in two inches of mud.
Sure knobbies would help, but without enough power they are useless.
And on the pavement they are Dangerous !!
If you want to feel the difference in efficiency for yourself, ride a regular bicycle with knobby tires then swap the tires for smooth street type tires.
The difference is more than noticeable.
Why waste all that energy pushing and pulling slippery knobs when the power output is so limited by batteries and our own human lack of power.
It is true however that if you are a hard core down hill dirt racer, and you don't have to pedal your ebike back up the mountain, then big knobs help with grip while cornering and braking, but most of us don't ride like that, and I'm too old for that.
Blue Mountain resort in Collingwood Ontario offers a ski lift for bicycles to get to the top of the hill.
If that's your speed and you want to spend the money on lift tickets, then ditch the ebike and get a hard-core downhill mountain bike with big powerful knobby tires
98% of riders don't ride like that.