Thanks for all the help.

I went with 245/75R16 for the front tires (same size as on the rear tires), Firestone Destination LE2. I used Tirebuyer as they were the cheapest (although Tire rack was very close in price). The tires came in two days.

However, the Pitman arm had to be replaced, as it was worn after 170,000 miles. The truck is much more smooth and stable at highway speeds now after the alignment.