Hello gavinp,
at Stridaforum!
According to Wikipedia/Strida/series you’re right.
Even if the LT wheels would fit, you would have another problem:
LT wheels do not have a brake drum, these wheels are made for a disc brake.
And the 3.3 frame doesn’t have a brake caliper mount…
I guess you should check (or let check) the spoke tensions of your wheels (maybe once or twice a year), if they’re OK there should be no durability problem at all.