Once again, it takes the entire system to be right for you to get the best ride quality. There IS no 'one size fits all' way to 'tune the ride'.
Some folks want a softer ride, others like a stiffer ride. Some want a lot of uptravel, others want to have a ton of droop and be sure the spring stays tightly seated.
But here is a start...
The purpose of a suspension is to allow the unsprung weight of a vehicle (the tires and axles) to move up and down easily over road inconsistencies while allowing the vehicle's sprung weight (the part you sit in) to remain stable. That's it in a nutshell. Easy to say, not so easy to achieve.
There are 3 basic parts to a suspension. Tires, springs, shocks. Tire sidewall is an important part of the system. It acts as a spring to help absorb road shock. Too narrow, thick, stiff, hard and instead of absorbing road shock it will transmit it farther up into the suspension. This is why (for a TJ) you want a soft sidewall with lower tire pressure. This allows the sidewall to flex over imperfections in the road. Decrease sidewall (run 18 or 20" rims), increase load range or psi and you stiffen the ride, ALL OTHER THINGS BEING EQUAL.
Springs perform 2 basic things. They establish static ride height and allow the unsprung weight to move while isolating the sprung weight. Ride height is easy. Want it to ride higher? Use a longer (taller) spring of the same rate, OR use a higher rate spring that won't compress as much with the vehicle weight. Sounds easy, but it's not. Higher spring rate means the spring will compress LESS when a vehicle hits a bump ALL OTHER THINGS BEING EQUAL. That means the spring will transmit the shock farther up. Same as a stiffer tire. The difference is, there IS no farther up. Which means that shock is transmitted to the sprung weight of the vehicle (the part you sit in). Use a softer spring and it can compress much easier when the tire moves upward. This means the spring can absorb more of the shock, preventing it from going into the vehicle. BUT THERE IS A CATCH! A softer spring will continue to oscillate easier and for a longer time than a stiffer spring. And this will transfer into the vehicle as repeated bouncing long after the road shock has gone. So you have 2 choices. A spring that doesn't compress much transfering the road shock into the vehicle (high spring rate) or a spring that compresses easily that absorbs the road shock but transfers the continued oscillations into the vehicle. AGAIN, ALL OTHER THINGS BEING EQUAL.
The 3rd part of the suspension is the shock absorber. It does one thing, and one thing only. It restricts the movement of the spring. Yes a nitrogen or gas shock extends by itself, but that is negligible to the suspension and only a byproduct of the gas used to prevent aeration (foaming) and shock fade. So, since the shock only does one thing (again, control the movement of the spring) let's look at how IT affects vehicle ride.
The soft spring encounters a road shock...absorbs the shock by compressing, preventing the shock from transferring into the vehicle (so far this is great!) But then wants to continue to bounce. Well, a shock is made to restrict that bouncing. Restricting the soft spring from continuing. Stoping the bouncing from affecting the vehicle. Between the correct tire design absorbing some of the road shock, transferring the rest upward, and that compliant spring absorbing the remainder of the road shock, and the shock absorber having the propper valving to control the excess movement of the softer spring, the unsprung weight is able to smoothly move over the surface with minimal transfer of shock into the sprung weight of the vehicle. Just beautiful because ALL parts of the suspension are working together properly to allow the vehicle to move smoothly over the surface. BUT... (there's always a but in there, isn't there.)...
BUT...what if you stuck a spring in there with too high of a spring rate? LET'S SEE...
Tire hits a bump. Good tire selection means part of that shock is absorbed by the sidewall, the rest is transferred up. Remainder of shock is transferred to the spring, but now the spring is too stiff to compress (enough), so the remainder of that shock is transferred into the vehicle. What about the shock absorber??? Well, it did nothing. Remember the shock absorber can only control the motion of the spring. The hard spring didn't compress, so the shock absorber does little to nothing about the suspension's ability to dampen the road inconsistencies.
ONE OTHER WAY THIS COULD WORK... good tire choice...nice compliant spring of the proper height.... shitty choice in shock absorber. It's calving is too restrictive. It is so stiff that it prevents the compliant spring from it's initial movement. Therefore instead of the spring being able to absorb the road shock, it gets transferred up into the vehicle. No matter how perfect the spring is matched to a vehicle, poor shock absorber choice can still cause a harsh ride quality. But..(another one? Geesh!) But no matter how perfect a shock absorber is, if the spring is too stiff to compress over road imperfections then the shock can do little to improve things.
Hopefully this is helpful in explaining how the different parts of a suspension interact with each other and how a poor choice of one part can negate the other parts from doing their job.
perfect ride.
