I've mentioned numerous times I Shinkos are awesome. Built on previous Yokohama plants.
I'm on 5th set of Shinko radials on my CBR600RR and they've all worked great. Used them on both my pre-gen and new-gen 250s. Even on track they've been amazing. Better than original factory tyres.
As for following groves on road, make sure they're NOT overinflated.
Pressure recommendation is corporate CYA lawyer-speak for max-load capacity of tyre when bike is at max GVWR (with passenger) running at top-speed of tyre rating (Z=150mph, W=168mph). Unless you carry passengers and ride at tyre's top-speed constantly, then that pressure is not relevant to your actual riding conditions.
Link to original page on YouTube.
Better to use suggested pressures from tyre-manufacturers themselves. Find similar model to yours and add 10% pressure over max-grip pressure below for street-riding. Best to use max-grip pressure for best braking & cornering performance rather than max-load rating. Which results in poor grip and bad tyre life.
