I've been trying to figure this out for some time... You take a tire like what comes stock on the RX-8 (Potenza RE040), with a really plain-looking tread pattern, and they have excellent dry AND wet handling (from just looking at them, I'd say they wouldn't do so well in the rain...). Then you have some other tires with these fancy-looking, swept, wide-channel treads that don't to quite as well, even though they absolutely look like they'd do much better... What really makes one better than the next? Tread compound? Some complex method of tread design we mere mortals will never understand?