You could use a fish scale How many pounds pressure before the car starts to roll on each type of tire?

(At the same pressure, of course.)

Or, what I did: find a gentle hill with a long run-out (I used an empty parking lot). At the same tire pressure, roll the car in N from the same start position multiple times, and mark the pavement with chalk wherever it stops. Change tires, rinse, repeat. Compare the 2 sets of chalk marks.

Since you have 2 Mirages, you could do the comparison without having to change tires! It'll take you 15 minutes, tops.

There was a big difference in rolling resistance when I did my own tire comparisons, here:

Testing rolling resistance of the Various Tires of the Suzukiclone Fleet (RE92 wins)