Thread: Race Tires 2017
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Old August 5th, 2017, 10:11 PM   #61
DannoXYZ
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Quote:
Originally Posted by Twinshock750 View Post
As I said also, there's a lot of variables which can create different grip levels. Case in point. Years ago Bridgestone said the difference between a BT50 and BT50SS was NOT compound and in fact they made the tyres with the same compound, the difference was construction.

Good point about fitted etc!

The durometer has been great for a bit of piss taking in the pits....chat to the guys, show them the durometer, measure their tyre, give a slight shake of the head and suck a bit of breathe....irrespective of whatever it shows!
Quote:
Originally Posted by tgold View Post
Having worked in the urethane casting industry I can tell you that durometer readings are not directly related to grip. Case I point: Many race tires are harder at cooler ambient temperatures than street tires, yet they get considerably gripper when brought up to temperature. Yes, they get softer, but that is when they are heated by warmers or use. So checking durometer readings of various tires at ambient temps is of no value. By the way, you do know that the A13 is a multi compound tire right? So where you take your durometer readings would make a difference in the result.
Yeah, there's more than just rubber compound. Casing construction makes HUGE difference, but neither Pirelli nor Dunlop is giving us much information about their construction. About all we know is there's nylon threads involved, and some steel belting, but nothing specific that we can correlate with performance behavior.

I just happen to have three of tyre models we're talking about: Pirelli Supercorsa, Dunlop Alpha 13, and Alpha 13-SP.


Did a quick test of casing stiffness at room temperature.

Link to original page on YouTube.

Pirellis are closer to race-tyres, they require warmers and take a long time to soften up. At which point, casing's and rubber's more flexible than Alpha 13?

Alpha 13s are more DOT-R tyres that warm up quickly, but doesn't change flexibility or rubber grip as dramatically as the Pirellis.

Alpha 13 SPs, I guess... are an attempt to bridge that divide? It has softer rubber than Alpha 13 regular. The casing is much softer at room-temp and probably won't get that much softer when warmed up. It was designed to not need warmers, thus the "pre-warmed" flexible casing at room-temp. But is it as flexible as the Pirellis @ operating temp?

Anyone have lap-time comparisons of these tyres? With same bike & riders?

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