Spitfire has come up with a new urethane formula called Formula 4 and we have the new wheels in house. i was fortunate enough to get a set of the F4 in Spitfire's classic shape at 54mm and 101 A durometer this summer to try out and i've done a bit of skating on them. Keep in mind that i typically ride 54mm and my usual set-up is in the 99 to 100 hardness so i picked a wheel set that was in my normal riding range. They do come in other shapes and harnesses.
The new formula claims more speed and better flat spot resistance. Fast they are. Same great shape as usual (in this case) and more slide and durability. i was 4 wheel power sliding, 180 sliding, all over good distances and the wheels would not flat spot. They maintained their shape and rode just like they did when brand new. The only difference to the wheel was road/tar dirt on the riding surface...that was it.
Also new with the F4 is the color, which i also liked better. Rather that the usual, really bleached out white look that brand new wheels have the new formula has a more bone colored, natural white tone to them. Sure, within a few skates wheels tend to take on that color anyway but i really liked the bone color on my skull graphic deck from the moment i took them out of the packaging.
If you hate flat spots and like Spitfire shapes come on down and get them, in multiple sizes and shapes here at the shop.