Just got off the phone with an engineer from Metzler, 30 years in the business and an avid motorcyclist: first of all, thanks to Metzler for actually calling me back. The guy was in a hotel room in Italy, spent all day on an airplane, and called at 1:00 am his time!! Class act. There is an extra belt in the "p" spec tire. The "p" spec was developed as a hayabusa specific tire to handle the extra weight (heat build-up) at warp speeds and to assist with stability when bending light. After looking at the specs, the tire is closer to a 198 then a 190, just like the oem Bridgestone BT056ss. This tire was developed as a result of Suzuki's requirements for the busa, not the other way around. Now, will a regular spec M1 work? You bet. If it lets go at 185, your widow can skip the call to Metzler....their fitment chart specifically calls for the "p" spec tire to be used on the busa. After picking this guy's brain, I'm having the local dealer stock a set of p's just for me...my fifth set of M1's will be "p" spec. moondog out.