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How strictly do I need to adhere to the recommended tire pressure on the sidewall?

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How strictly do I need to adhere to the recommended tire pressure on the sidewall?

Old 07-10-14, 09:30 PM
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How strictly do I need to adhere to the recommended tire pressure on the sidewall?

I just put two new tires on my road bike and the sidewall says inflate 85 to 120 PSI, but I only inflate the rear tire to that range; typically I only inflate the front to 70 PSI. Is that still consider ok? The old tires only said maximum pressure 120 PSI and I've never had a problem with 70 front, 85 rear.
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Old 07-10-14, 10:16 PM
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Originally Posted by jsdavis
I just put two new tires on my road bike and the sidewall says inflate 85 to 120 PSI, but I only inflate the rear tire to that range; typically I only inflate the front to 70 PSI. Is that still consider ok? The old tires only said maximum pressure 120 PSI and I've never had a problem with 70 front, 85 rear.
Don't exceed the maximum. Beyond that, tire pressure is really a matter of how loaded the wheel is. Assuming you're running the same size as before, you should be fine.
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Old 07-10-14, 10:33 PM
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Actually; it depends on the tire. Almost all tires will last longer with higher pressure due to less cyclic deformation of the tread and sidewalls. On some tires, such as Specialized Armadillos, low pressure results in tread separation at surprisingly low miles and 5 to 10% over pressure seems to have no adverse effect.
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Old 07-10-14, 10:56 PM
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The tires are Schwalbe Durano size 700x28; old tire is Kenda something also 700x28.

I didn't see much difference between 70 and 80 PSI on the front but I could certainly feel the difference over rougher pavement on the Kenda's. I almost feel like the Schwalbe is a bit more supple at 70 though. I guess I'll try out 80 PSI tomorrow or over the weekend.

Last edited by jsdavis; 07-10-14 at 10:59 PM.
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Old 07-10-14, 10:59 PM
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You want to inflate the tire so that the tire deflects (squishes) a little bit. It depends on weight and tire width. This article explains it and has a nice reference chart.

https://www.bikequarterly.com/images/TireDrop.pdf

If the pressure is too low, you'll have more rolling resistance, the handling will be squishy, you'll be prone to flats and rim damage, and the tire can even roll off the rim. For my commute bike tires (25 mm) down around 60-70 psi they are feeling really soft and squishy/scary. I usually run about 100 psi. You can exceed the maximum listed on the tire, though you won't normally need to.
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Old 07-10-14, 11:12 PM
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Originally Posted by jyl
You want to inflate the tire so that the tire deflects (squishes) a little bit. It depends on weight and tire width. This article explains it and has a nice reference chart.

https://www.bikequarterly.com/images/TireDrop.pdf

If the pressure is too low, you'll have more rolling resistance, the handling will be squishy, you'll be prone to flats and rim damage, and the tire can even roll off the rim. For my commute bike tires (25 mm) down around 60-70 psi they are feeling really soft and squishy/scary. I usually run about 100 psi. You can exceed the maximum listed on the tire, though you won't normally need to.
That article is how I decided what pressures to run; actually that article recommends I run closer to 60-65 on the front. I have 700x28 so pressure doesn't need to be as high as your 25s. Only reason I brought up the issue is because the sidewall goes against this article. I wouldn't dare run the back tire at 60-70PSI since I carry all my riding gear in on a fanny pack lashed to my rack. The front is ok at 70 though.

Also Schwalbe lists the same pressure range recommendation for 23, 25, and 28 of the same model tire so that looks a bit strange to me.

Last edited by jsdavis; 07-10-14 at 11:16 PM.
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Old 07-11-14, 07:36 AM
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Originally Posted by nfmisso
Actually; it depends on the tire. Almost all tires will last longer with higher pressure due to less cyclic deformation of the tread and sidewalls. On some tires, such as Specialized Armadillos, low pressure results in tread separation at surprisingly low miles and 5 to 10% over pressure seems to have no adverse effect.
Excessivly high pressure will greatly reduce the amount bumps and vibration the tire will absorb. it also reduces grip, particularly on a rough or wet road. If a 28 is damaged by running at 70 pounds with with a typical rider's front load, it's junk.
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Old 07-11-14, 07:47 AM
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Originally Posted by jyl
You want to inflate the tire so that the tire deflects (squishes) a little bit. It depends on weight and tire width. This article explains it and has a nice reference chart.

https://www.bikequarterly.com/images/TireDrop.pdf

If the pressure is too low, you'll have more rolling resistance, the handling will be squishy, you'll be prone to flats and rim damage, and the tire can even roll off the rim. For my commute bike tires (25 mm) down around 60-70 psi they are feeling really soft and squishy/scary. I usually run about 100 psi. You can exceed the maximum listed on the tire, though you won't normally need to.
^This.
There is also an online calculator for it: Bicycle tire pressure calculator

After measuring the weight on each wheel of each bike, putting in the calculated pressure, then riding them, I'm sold on it.
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