For clarification, 10 spokes have 10 spokes, and a swirl pattern and come chrome or painted. Made for right and left side patterns,, and have small 2.75" or so centercaps.
Octastars have 12 spokes and are for either side and have 8" or so centercaps.
255 50R 16's are about 3" shy from the stock 225 60R 16's height. Overall diameter would be way smaller. Bottom line is you could probably run them but more than just fuel mileage would suffer.
225 60's are much more common, and I'm sure you could pick up a used pair pretty cheap.