Remember, HO is 1:87 scale, and O is 1:48. Code 83 rail represents much bigger rail in HO than in O. In HO, code 83 would be 7.2 inches tall, in O it would be 3.9 inches tall.
If you are modeling in O, as in ON30, the lumber, the people the buildings are all O scale 1:48 (we hope). So the size of the ties generally are going to be bigger for ON30 than for HO. Unless it is a very rustic logging line or mine, I think HO ties are going to represent something way too small in O.
