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Discussion Starter · #1 ·
Thanks for reading.

I've been looking at different sets of tires for my hard tail. I need to pick a set mostly for trail riding, and right now my concern is wet weather performance (given the mud we ride through). I'll be buying a summer set in a few months so I don't plan to run these year round.

At any rate, as I've been reading the different descriptions for tires, they often list the bead type and compound.

For example, the Rollx Pro D2 tire on the specialized website lists a "60 shore a" compound for the shoulders and a "70 shore a" compound for the center. Now, the site gives a basic detail of the benefit - for example the 60 shore a on the shoulders says for better cornering and the 70 shore a on the center says for lower rolling resistance and durability. I get that. My question is, why? What does the "70", "shore" and "a" actually mean and how does all that translate in to better cornering or durability/rolling resistance?

As for the bead, the same tire says it uses an Aramid bead, for light weight and foldability. The 'aramid' in the description links to a quick description that basically says "for light weight and foldability", just in more words. What are the benefits of different types of beads, and what are the different types available?

Thanks for your help. And if it turns out I just suck at searching, feel free to pick on me, the only requirement being that you link me to the golden thread that you're picking on me for missing.

Thanks.
 

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A lot of tire makers are now using multiple rubber compounds in the same tire. Usually a harder comound might be used for the center tread to prolong tread life and a softer compound will be used on the edges of the tire to enhance grip while cornering. Softer rubber usually means more grip but tire life suffers, a hard tire compound will give you long tire life but grip will suffer. Dual compound tires give you a tire with the least amount of compromises.

There are two types of beads on mtb tires, there is folding beaded tires (also called kevlar or aramid beaded) and then you have wire bead tires. Folding beaded tires are usually lighter but slightly more expensive than wire beaded tires. Wire beaded tires actually have a wire imbedded in the edge of the tire to keep the tire on the rim, this wire make the tire heavy. Another advantage that folding tires have over wire tires is that they can be folded compactly for storage and sometimes they are easier to put on your rims than wire tires.
 

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Shore hardness refers to a standard ASTM test for the hardness of elastomers

It might be how far a specific rod pokes into a specific square of rubber with so much weight, anyway something like that.
 

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Discussion Starter · #4 ·
I found a sweet wiki on the shore durometer: http://en.wikipedia.org/wiki/Durometer . It details the test and how they measure the results. Now I understand that 0 is softest and 100 is hardest.

Anybody know what rating one would desire in a winter tire? temps ridden are 30-60 degrees (typically, though some days hotter).

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I believe my Nokian studded tires are a 60 durometer tire. They didn't set-up at -30 C, and I have about 2500 km on them.
 
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