BT23, a radial for modern sport/touring motorcycles. They came as OEM on my FZ8. They are a good tire for sport/touring, with touring as the primary focus. They can handle a lot of weight but have a very stiff carcass. Bridgestones typically are quite stiff, as those who follow MotoGP will know. They take a long time to warm up and aren't especially compliant at high lean angles unless the pressure is set correctly and they are fully heated. Bridgestone is the spec tire for MotoGP, so all competitors must use them. My GSX-R had the BT016's OEM, same story, very stiff carcass, poor feel on the street, takes a long time to warm up, and will never warm up on the street at listed pressures.
Both those bikes are now fitted with Dunlop Q3's, a vastly superior tire in all respects. Not a good choice for the CB1100, though, which brings me to the point here.
The CB1100 is an old-school motorcycle that works best with a certain design and size of tire; modern, wide radials are not the right choice for it. Honda chose the 110 and 140 front/rear for the optimum handling and ride quality. A narrow tire provides very neutral handling, as well. The farther the contact patch is offset from the centerline of the motorcycle at lean, the less neutral will be the handling. Anyone who rides the modern machines (those with 120/70-17 front and 180/55-17 rear or larger) knows the handling is quite different from motorcycles with narrow wheels/tires like our CB1100, once the bike gets heeled past 20 degrees or so. The handling is much, much different nearer to maximum lean angle and requires a different riding technique from old-school machines. Bump steer in particular is markedly different, with a lot more of it being fed into the chassis with the modern sizes.
The chassis and suspension of modern bikes are designed to work with wider tires effectively but our CB1100 doesn't have these design features. It's optimized for old-school tires and narrow rims. This is something to keep in mind. Instinct says to us, "Well, let's find a new, modern tire to put on our CB1100", but in truth, today's tires which are made in sizes for our CB1100 are indeed modern in design; they just fit narrower rims. We can get radials or bias-ply tires that are a perfect match for the CB1100 from quite a few manufacturers, Bridgestone, Avon, and Continental coming quickly to mind.
Bridgestone does make tires for our bike, but the BT023 and similar types are not in that group. The 160/60-18 rear, according to Bridgestone's fitment chart, is designed to work best on a 4.50-5.00 inch rim. Our bike has a 4.00" rim, and the maximum size recommended for that rim is Bridgestone's own 150/70-18, which can be had in the BT45 bias-ply or (in European markets) the BT54 radial.
We can put on a wider tire but to what advantage? The contact patch is no larger, as it is determined only by the tire pressure and the weight of the motorcycle. With a larger width on a too-narrow rim, we move the contact patch outward more with increasing lean, where it's less compatible with the bike's design and changes the handling and performance of the motorcycle.
