These tires are used exclusively on the track. I purchased 71 soft rated tires. You need to run these tires in, following the manufacturers instructions, allowing 24 hours to cool. Running in then completed. Management of pressures is critical if you want optimum grip and maximise life. Excellent tires for the money. Grip so good you almost need goggles to keep your eyeballs in. And they get up to race temperature super quick.
I run Toyo R888 in the wet, but find the Z214's fine on a damp track when up to temperature. Haven't tried the 51 medium rating tire. Interesting to see if the new Toyo R888R in soft, will allow me to run one tire type, wet and dry.