Originally Posted by hokiefyd

I think tire weight and "ride quality" are more indirectly linked than directly linked (on a bicycle).

Tire weight and ride quality is much more relevant in an automobile, where a spring and damper have to act against tire mass that moves upward from a bump (if the spring and damper were not there, the tire would keep traveling upward until gravity eventually pulled it back down). From that respect, wheel and tire weight in an automotive situation matters in a way that is not relevant to bicyclists.

That being said, tire materials and construction have a lot to do with ride quality on a bicycle, and it's here where I think weight is only indirectly correlated. A heavier tire is so due to a number of factors, but a leading factor is the presence (or the lack) of a puncture barrier. These are likely getting better all the time, but I think it's generally true that there's a degradation in ride quality. A puncture barrier usually reduces flex and "suppleness" in a tire, and makes it less compliant. Another leading factor in weight is the rubber and casing material. Thick casings (typically with a lower threads-per-inch count) are also generally less supple than thinner casings that may have a higher threads-per-inch count.

Combine an inexpensive tire (with a low TPI) that also has a puncture barrier (like a Bell tire with Kevlar), and you have the recipe for a really "dull" feeling tire. It doesn't feel dull because it weighs more; it weighs more because it has attributes that make it feel dull.

Another factor that influences speed and acceleration that is only indirectly related to weight is the rubber compound. One with a high rolling resistance is generally more likely to be found on inexpensive tires (that also typically weigh more, due to the use of non-exotic materials). More expensive tires, that often use more sophisticated design, material, and construction, that also may tend to weigh less, may also have a more advanced rubber formulation that doesn't consume as much of the rider's power to just push it down the road.

I tend to stay away from heavier tires because I prefer the ride quality that usually comes with lighter tires. I would agree with the notion that mass itself is not terribly relevant, and certainly not to me. I don't ride even close to The Limit to where an additional 1% one way or the other makes any difference. Most of my riding is toodling along with the kids on our way to the park, or down a trail along the Shenandoah or the Potomac.