The absolute overall weight of the wheel & tire combination should, of course, be as light as possible without losing function since it's 100% unsprung weight. However, this has no more effect on acceleration than the same weight removed from the roof or the driver.

A valid yet inexpensive test of rotational inertia (how much power is used to spin a wheel up to speed) could be a coast-down test.
Measure the actual diameter, from this calculate the speed in RPM to turn a specific MPH. Example: a 26" OD wheel = 81.68" circumference, or 6.807 feet per rotation. At 2,000 RPM that's 155 MPH.
To allow different diameter sets to be compared, the second T & W combo should also be spun at 155 MPH (not the same RPM unless it's the exact same OD) for comparo. Two sets with identical weight and OD may have different moments of inertia depending on where the weight is located: rim or hub.
Record the time in seconds to stop from speed, the one with the shortest time is the lighter MOI (duh). No, there is no easy math to say how much, just which wins.

Did I leave something out?