Morrag is right but........ So is Mr Manky
if you use self centering nuts (They have the loose tapered section that presses into the tapered hole) you should be OK.
However....... Check the wheels for signs of damage and make sure they have a fair amount of meat around the hub area.
The ultra modern jobbies that have very small centres or the multi fit ones (ones with eight or more holes) are to be avoided especially on a hard tail trike. Width of the wheel and offset also increase the chances of a failure so avoid extra wide ones.
I'm not repeating myself but my dinner is