Thread: Race Tires 2017
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Old August 4th, 2017, 09:58 PM   #56
Twinshock750
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Name: Alistair
Location: Auckland NZ
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Motorcycle(s): CMR TZ750 Yamaha, McIntosh TZ350 Yamaha, OW01 Yamaha, 300 Ninja Lightweight production Bike

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Quote:
Originally Posted by Zaph42 View Post
I have a shore A durometer also. Let me tell you something, it's only good for one thing and it's not judging a tire for stickiness. Tires change state at operating temperature and their hardness is only one component of what makes them stick. It's more about their composition. Also some race tires measure hard when cool, then soften up a lot when at temp.

The durometer is good for checking tires for their age or heat cycles. Know what a new tire measures then check during it's lifespan for an increasing number. Note that mounted/inflated often measures differently than unmounted, so be sure to standardize.

Hmmm, never heard of the Alpha 13SP, what is that?
In 32 years of racing, I've yet to see a tyre which is hard relative to another tyre, become softer and essentially grippier than a tyre that is already soft....but hey it could happen.

BUT; We're using it (the durometer) for base lining tyres mostly and interestingly, what we are seeing is consistent with where the tyres are falling on the relativity scale in terms of grip etc. It's not something I'd hanging my hat on....but we are seeing consistent results relative to grip, at this level. In this case as you have probably found, its trying to (badly!) get some objective testing into a very subjective world...

DR11 front at 65 measurement, RS10 and Alpha 13 at 53-55 and DR11 rear at 53....let's face it the Dr11 is a competent tyre, but not at a level of of the Alpha 13's etc for grip.

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!



Alpha 13sp:
1) is the control tyre for MA RC Cup in 2017
2) An updated Alpha 13

There's now an Alpha 14 out too just recently as well.
http://ridersnavi.com/encyclopedia/index.html
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