# Vittoria Zaffiro Pro Slick tires on Shimano RS10 wheelset TIRE PRESSURE



## TallCoolOne (Jan 18, 2010)

I have been some internet searches for recommended tire pressures for my wheels and tires. 

I weigh 250 lbs. I have a Cannondale CAAD9 5. My tires are 23mm Vittoria Zaffiro Pro Slick tires on a Shimano RS10 wheelset.

Before anybody says anything about the appropriateness of this wheelset...I KNOW THEY AREN'T GOING TO LAST LONG. They came with the bike and I don't have the funds to upgrade right now. I am saving up. I promise.:thumbsup: 

Does anyone know the recommended tire pressure for this setup? 

Does anyone have any suggestions for what tire pressure I should run in each tire?

Why do people run different tire pressures in the front and rear tire?


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## Hank Stamper (Sep 9, 2009)

TallCoolOne said:


> Why do people run different tire pressures in the front and rear tire?


Because more body weight is distributed to the rear.


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## TallCoolOne (Jan 18, 2010)

That makes sense.


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## JCavilia (Sep 12, 2005)

Pretty high. At your weight, that's the answer. The precise answer depends on some other variables, especially road conditions and whether you ride "softly" -- i.e., avoiding obstacles and unweighting to absorb the ones you can't avoid. What you want in tire pressure is just enough to avoid pinch flats. At your weight, with those tires, with "average" road conditions (not perfect, but you don't hit a lot of big cracks and potholes), that probably means something like 120 rear and 110 front -- maybe more.

That's going to be a harsh ride. You'd be well served to run larger tires if they'll fit on your frame. 25's, or even 28's if they'd fit, would allow you to run lower pressures and have a smoother, faster ride and much better cornering.

You run higher pressures in back because there's more weight on the rear wheel.


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## TallCoolOne (Jan 18, 2010)

Will you really be faster on a wider tire? I am a newbie so please forgive my ignorance. I had never heard that. I would have "assumed" that a wider tire would have more rolling resistance making you slower in theory.

When these wheels wear out I plan on upgrading to a set of Continental Ultra Gatorskins or Grand Prix 4000.


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## TallCoolOne (Jan 18, 2010)

Does more psi slow down the occurance of pinch flats?


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## JCavilia (Sep 12, 2005)

Pinch flats happen when a sharp obstacle (like a rock or the edge of a pothole) fully compresses the tire, so the tube gets pinched be tween the rim and the object. Higher pressure helps avoid that, by providing greater resistance to that force. A larger tire helps avoid it without higher pressure, because there's just more distance between the road and the rim.

Very low pressures make for more rolling resistance, and on a very smooth surface (like a board track) very high pressure makes for the fastest rolling. But in the real world you reach a point of diminishing returns with increasing pressure, because the hard tire bounces you around, reducing contact with the road, and slowing turns especially.

That's why a wider tire would likely be faster in your situation -- because it would let you run lower pressure. It would be much more comfortable, too. If I were you I'd be looking for larger tires right now, if you have the frame clearance. Tire brand and model is less important than size. The pressures you'll need with those tires are gonna beat you up, IMHO, and make your riding less enjoyable.


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## TallCoolOne (Jan 18, 2010)

Thanks for the input so far everyone. You guys are putting on a clinic of bicycle knowledge. I appreciate it.


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## exracer (Jun 6, 2005)

I can only tell you the pressures I was running when I weighed 235. It may vary slightly for you. Front 110, rear 120, that's for 23 mm tires and I didn't suffer any pinch flats at those pressures. Now that I have lost 65lbs, I'm running lower pressures.


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