Is this a new bike that you don't have a lot of miles on? If so:
1) Get a good pair of shorts.
2) Make sure the bike fits you correctly before changing any components.
3) Get at least 500 miles on before changing any components.
4) Once you have a good base get your sit bones measured and try a few saddles on a trial program. It took me 6 weeks to find the right one.
5) Tires should be down at the bottom of the concern list.