Soft comfortable ride on a Nightster LOL.
But seriously, tires "ain't gonna do it".

The front fork springs are very soft as is.
The rears shocks have limited travel, I believe only 2.75 inch fully extended.
Then there is the thin seats.
I'll say Nightsters ride rough

So, it may be you are bottoming out the suspension and are reaching the discussions of many on this forum

Yep, aftermarket fork springs (Progressive) and setting your front sag is well worth the effort and cost.
Many install the longer 12.5 inch rear shocks (which was factory length for Europe). and costs can range from used "take off" to Ohlins.
Noting with longer shocks one could say you will lose your visual stance/ bobber look.

So, first set, set your front and rear sag an see where you are at suspension-wise.
Then decide on suspension modifications.

However, a thicker seat may also be the first answer to your comfort question.

And , to answer your question, I use the OEM HD Dunlops, as I don't race around (corners or high speed), or ride in rain.
I also use the factory PSI suggestions 30 front, 38 rear.
Lower pressure would also function as a softening of your suspension, in a straight line.... but on face value I do not recommend that.

Good luck, enjoy your N.

 

Yessir - Im in the market for a mustang seat. Im shopping around the "used" marketplace before I bight the bullet on spending $400. Im torn between the Shinko's and Dunlops. The Shinko tour masters have really good reviews, that I'm seeing.

 

That thing is beautiful man !!!!
now I wanna get me a sporty

 

Mustang seats are awesome. I’ve owned a few and loved them.

The Shinkos are a decent tire, especially considering price. In my experience they wear quickly but again, at the price they seem to be worth it.

 

A few more pictures of the bike. Thanks for all the help so far.

 

Good looking real Sportster