Ribbed tires have the tread grooves running around the circumference of the tire. The Hondas of the era were all designed to use this popular, at the time, design type. If you want to know how sweet these bikes handled when new, seek out this type. As pavement grooving became more widespread, ribbed tires fell out of favor, as the bike will feel "squirely" as the tire tries to follow the street grooves. While not actually a performance issue, the bike feel left inexperienced riders uneasy and left severe operator induced butt clenching. Being an ex Navy man, I learned that having the deck feel like it's moving about, really didn't change the responsiveness or controllability of the bike. It still went where I wanted, when I wanted, the seat just moved about while doing so. It really wasn't all that unpleasant a "massage", if you think of it that way. Though it did cause me to double check the suspension components and tire pressures with more scrutiny.
The "modern" tread designs have tire grooves running at angles to the tire rotation. These are less likely to follow pavement grooves, which inspires more confidence in riders, so they can drive well beyond their limits.
However, this design relies more on contact patch size for traction while leaned over, than the ribs doing their grab thing under lateral loads. For the same narrow size tire with the same rubber compound, ribbed tires corner better on these bikes than the "modern" tread designs. Of course, road surface composition/condition will play an important role in max traction scenarios.
Cheers,
