Implement tire size question.

I have a New Idea hay mower that needs new tires. I would like to get as close as original. It came with 5:50-16 tires. The closest ones I found was from Miller Tire but are 5:00-16. Would this size difference look funny on it or would you even be able to notice it.

Also, does anyone know where I might find manuals (operators, service,& parts) for for this? It is for a New Idea M/N 30A mower. Thanks.

I recently bought a pair of 5.50-16 tires and tubes from Tucker Tire, but they are 3 rib. Maybe that would be right for you?