Chap -
I agree that it is alternating bolts that count, but I'm not sure I agree (or disagree) with the measurement. If you Google around the Internet, you will find some references that say "center-to-center", but most say that
for 5-lug wheels only, the proper measurement is "center-to-far side".
Among the former are
http://www.tirerack.com/wheels/tech/....jsp?techid=92. I think that they confused themselves with their tricky diagram.
Among the latter are
https://rsracing.com/tech-wheel.html
http://www.mrt-wheels.com/boltpattern.html
and others. This last one says you can also measure center-to-center, and multiply by 1.05.
On my TM, the measurement is 4.25 center-to-center, and 4.5 center to far side, which agrees with the 1.05 factor. And when I did my tire-size change, the tire shop referred to the new wheels as "5 on 4.5".
I believe that 5-on-4.5 is a common wheel today. Perhaps TM used a different wheel/axle in 1999. Regardless, if the actual measurement is different between the TM and the utility trailer, you will not be able to swap out the wheels.
Bill