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Inflating tires below the recommended minimum PSI pressure

Hello,

Last fall I purchased a pair of Specialized Armadillo 700x25mm tires. Their PSI range is 110 to 125. Really good tires, works great of paved road and packed dirt roads.

But since their minimum PSI is 110, it shakes way too much when riding on a loose gravel road section. Of course I slow down considerably when riding in loose gravel/dirt, but even when riding slowly the ride is still way too shaky.

Now, what if I inflate them below 110 PSI? Something like 95 at the front and 100 at the rear.

Is that dangerous? Can they wear down in a way that they will get fragile or unstable?

Thanks.

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19 comments

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Izaak30 | 9 years ago
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Thanks folks

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Charles-Antoine | 9 years ago
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Thanks everybody, really appreciate it!

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Izaak30 | 9 years ago
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Sorry I'm a bit thick and its early this morning so struggling to do the sums. Please help.
I'm 80kg and ride 25c tyres. What pressures should I be looking at? Thanks

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TheHound replied to Izaak30 | 9 years ago
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Izaak30 wrote:

Sorry I'm a bit thick and its early this morning so struggling to do the sums. Please help.
I'm 80kg and ride 25c tyres. What pressures should I be looking at? Thanks

It's personal preference depending on what you're comfortable with and the type of roads you're on.

Start off with about 100 psi in each and then take it from there. Add a bit, take a bit. See how it feels to you.

Just make sure you're not exceeding the maximum pressure.

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Simon E replied to Izaak30 | 9 years ago
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Izaak30 wrote:

Sorry I'm a bit thick and its early this morning so struggling to do the sums. Please help.
I'm 80kg and ride 25c tyres. What pressures should I be looking at? Thanks

I'd try 90 psi front, 100 psi rear. If it feels a bit soft add 10 psi.

It's not rocket science, even though some people like to make it seem complicated.

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glynr36 replied to Simon E | 9 years ago
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Simon E wrote:
Izaak30 wrote:

Sorry I'm a bit thick and its early this morning so struggling to do the sums. Please help.
I'm 80kg and ride 25c tyres. What pressures should I be looking at? Thanks

I'd try 90 psi front, 100 psi rear. If it feels a bit soft add 10 psi.

It's not rocket science, even though some people like to make it seem complicated.

This! People really over complicate it.
Just give it some trial and error and you'll soon settle on what works well with how you like the bike to feel

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TheHound | 9 years ago
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I'm using Vittoria Open CG Paves 27c at the moment.

The stated range on them is 110 - 130psi.

I think it's just the manufacturer playing it safe. I've no problems running 90/rear and 85/front.

Spectacular tyres by the way if anyone is looking for a qualility winter tyre.

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fukawitribe replied to TheHound | 9 years ago
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TheHound wrote:

I'm using Vittoria Open CG Paves 27c at the moment.

The stated range on them is 110 - 130psi.

I think it's just the manufacturer playing it safe. I've no problems running 90/rear and 85/front.

Spectacular tyres by the way if anyone is looking for a qualility winter tyre.

Agree with that, been using the 25s for some months now and at nearly the same pressures and they've been superb.

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sergius | 9 years ago
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Fairly unscientific, but I pump front/rear to 90 PSI every couple of weeks, I've not had a puncture in the last 18 months since I started riding again. I'm fairly light at ~63kg so that may be a factor - my old boss used to flat every couple of weeks and he was a fair bit larger than me.

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slam that stem | 9 years ago
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It's not about bulging its about bottoming out and you can only feel this by riding on them. Try 85 psi one ride then 80 the next until they feel too sluggish or you bottom out on them.

How much do you weigh?

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Charles-Antoine replied to slam that stem | 9 years ago
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185 lbs / 84 kgs

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chokofingrz | 9 years ago
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I inflate my tyres according to the 15% drop principle - the pdf linked above. For my low weight and 25c tyres that's about 90psi rear and 60psi front. Shocked? Yes it's less than the stated range, but the ride is just dandy. No punctures.

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bikecellar | 9 years ago
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Simon E | 9 years ago
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110-125 psi seems a very narrow range. My 25mm Durano (and Vittoria Rubino Pro before them) work well for me at 60-80 psi, I don't know what the sidewall says.

I would try a short test ride at 85 front & 95 rear, see how it feels. The main risk at low pressures is probably pinch punctures.

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matthewn5 | 9 years ago
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I run 700 x 23 Specialized All Condition Armadillo Elites on my winter bike. As its dirty and cold I often go a fortnight without pumping them up. They are sometimes at 60psi by the time I get to them. Never had the slightest problem, even with energetic cycling and hard cornering on much less than ideal surfaces. If you really do push it hard on an off camber corner just for fun they start to give way very gently leaving plenty of time to correct. Try 80 front 90 rear and relax.

If you want to do the pressures by the book, look at this, you'll be surprised how low the optimum pressure is on 25c tyres:

https://janheine.wordpress.com/2010/10/18/science-and-bicycles-1-tires-a...

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fukawitribe | 9 years ago
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I run Vredestein Fortezza Tricomp 23mm at 90/95 and Vittoria Open Pave 25mm + Hutchinson Fusion 3 23mm (tubeless) between 80/85 and 85/90 - never had an off moment as far as tyre integrity goes, the Open Paves could probably go a fair bit lower if the surface warranted it.

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CXR94Di2 | 9 years ago
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Yes, I like them. They are wearing well, even through the winter. There is a new version with better puncture resistance.

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Charles-Antoine | 9 years ago
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CXR94Di2: Thanks for your answer.

Are you happy with your Schwalbe Durano?

Do you sometimes go on dirt roads?

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CXR94Di2 | 9 years ago
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As long as the tyre doesn't bulge too much at the bottom I doubt the tyre would roll off the rim. I use Schwalbe Durano 25mm and run about 95-100 psi. Your other option is go 28 or 32mm if your frame allows.

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