I wasn’t trying to be disparaging. I see what happened, looking now. You converted directly from inches to meters.
A drive setup like the Rolling Plotter build might not be bad.I think that he originally used belts and then went to a gear drive system. Even simple R/C cars use some sort of drive reduction as a torque multiplier. I don’t know if stepper motors are quite required here, but maybe some R/C motors with speed controllers could do the trick if you have something to keep track of the amount of steer that you have.
For a mower application, I think that trying to keep to 2 tracks would be better, so 2 swivel wheels on the front, or more likely, have 2 driven wheels on one axle, so no differential drive for steering, but maybe one free swiveling wheel and one steering wheel that is servo controlled? I think that most lawn mower type wheels will slide on grass a little.