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Yokohama YK580 Tire - Quiet, Smooth, Grippy and Long-Lasting, But Not Perfect - Yokohama YK580 - Epinions.com
"Despite the fact that the traction in turns, acceleration and braking are excellent, the tires are not very suitable for spirited driving. They are not very responsive: it seems that the initial split second you turn/accelerate/brake nothing happens. Is it the fault of the progressive sidewall that gives you cushy/quiet ride? Maybe. With the YK520 this behavior diminished somewhat as the tread wore, but didn’t go away completely so there must be more to it than just the elasticity of the tread."
You've got tires that should last 3x longer and cost 80% of the RE050s Overall, that's about 1/4 the price on the tire. I would expect a significant drop in performance. Weak sidwalls suck for responsiveness.
Drive carefully!