# Tire pressure - follow indications on tire or not?



## ToiletSiphon (Jul 23, 2014)

I just bought a pair of Vittoria Rubino Pro III tires. There are instructions on the sidewall saying that min pressure is 100 psi and max pressure is 130 psi. That seems very high for a 25mm tire.

I bought these tires on Wiggle, which has the following chart regarding pressure for Vittoria tires (the Rubino pro III are 150 TPI).









Which recommandations should I follow? I'm 142 lbs, so I was thinking of going 95 psi upfront and 100 psi for the back wheel. I'd rather avoid pinch flats than have the most confortable ride.


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## velodog (Sep 26, 2007)

read this

https://janheine.wordpress.com/2016/08/22/minimum-tire-pressure/


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## dcgriz (Feb 13, 2011)

From the Vittoria site comes the following which when attached to the inflation pressure table makes the table to make more sense:
_It is impossible to make a general recommendation on inflation pressure for a specific bike and rider, the right inflation pressure depends on too many variables.
Frame and wheel material, construction and stiffness of these, weight distribution, asphalt surface, width and material of tires and tubes, weather and temperature, and not least riding style are the most important variables to find which is the right inflation pressure. In this view the following chart is only a starting point to find the proper pressure and it has not to be seen as rigid rule.
recom_tyre_pressure
For wet or rough roads, decrease by 0.5 bar (7.5 psi). For tubular tires, increase by 0.5 bar (7.5 psi). Minimum indicated pressures can be lowered only in the cases mentioned in the above chart.

The best way to fine tune ideal tire pressures is field testing a variety of different pressures. One method is to use a short criterium style circuit, preferrable with a variety of corners. Start with the suggested pressure and ride a lap. Each following lap, lower the pressure by 5psi until you feel the tires start to “wallow” or move a bit. This is your lowest pressure point. Return to the above table pressures and raise 5psi each lap until the tires start to bounce and skip/move across the surface. This is your max pressure. Decrease by 5 psi from here until you feel you have the best pressure for the conditions.
Keep a tire pressure log, including road surface, techinicality of the course,weather conditions, tire type, brand, and TPI. Finally, the bike you used and your weight on that day. Over time, this log will become a valuable tool for referencing tire pressures and road conditions in order to optimize your performancewhen on race day._

Start with 65psi front and 80 psi rear and go from there. If you do a lot of sprinting you may want to raise the front by another 5 psi.


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## Mike T. (Feb 3, 2004)

ToiletSiphon said:


> I'm 142 lbs, so I was thinking of going 95 psi upfront and 100 psi for the back wheel. I'd rather avoid pinch flats than have the most confortable ride.


I'm 175 and don't pinch flat at a max of 80f/90r and lots of times it's 70f/80r with re-pumps done at maybe 60f/70r. I've had one pinch flat since '86 (when I switched to hp clincher tires from tubulars).

If I was your weight I'd be on 23mm tires at my pressures.


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## Marc (Jan 23, 2005)

Yea...I ride 320TPI Vittorias and I don't listen to those cranked up PSI numbers. IRL, Roads are too rough for those numbers.


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## Mike T. (Feb 3, 2004)

dcgriz said:


> From the Vittoria site comes the following which when attached to the inflation pressure table makes the table to make more sense:
> _It is impossible to make a general recommendation on inflation pressure for a specific bike and rider, the right inflation pressure depends on too many variables.
> Frame and wheel material, construction and stiffness of these, weight distribution, asphalt surface, width and material of tires and tubes, weather and temperature, and not least riding style are the most important variables to find which is the right inflation pressure. In this view the following chart is only a starting point to find the proper pressure and it has not to be seen as rigid rule.
> recom_tyre_pressure
> ...


These are incredibly good suggestions.


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## cxwrench (Nov 9, 2004)

ToiletSiphon said:


> I just bought a pair of Vittoria Rubino Pro III tires. There are instructions on the sidewall saying that min pressure is 100 psi and max pressure is 130 psi. That seems very high for a 25mm tire.
> 
> I bought these tires on Wiggle, which has the following chart regarding pressure for Vittoria tires (the Rubino pro III are 150 TPI).
> 
> ...


Just how many pinch flats do you see yourself getting? Your plan is to purposely over-inflate your tires thus reducing traction (you go around corners on every ride, correct?) and reducing ride quality (which is 100% of every ride compared to what percentage of time you actually pinch flat....000001%?) rather than inflate to a pressure you'll like more for the 99.9999% of the time you're not flatting?

For 142lb rider, on 25mm tires, depending on rim width, fit/geometry I'd recommend 80 psi rear and 65-70 psi front.


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## ToiletSiphon (Jul 23, 2014)

Lol, I'm currently at 95/110 on my 25mm aksion tires. Used to run even higher. I'll reduce that at bit with my new tires. 

Envoyé de mon XT1563 en utilisant Tapatalk


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## cxwrench (Nov 9, 2004)

I'm 175 and I use 85/75 for 25mm tires and we have some crap pavement here. I have NEVER pinch flatted on the road. Most likely cuz I keep my eyes open.


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## duriel (Oct 10, 2013)

You guys seem to run your front tires a lot lower than the rear. When I do that and am going around corners, my fronts seem so spongy compared to the feeling I get from the rear. Also when standing the increased wt make them spongy again. 
Do you run more even pressure when under more difficult 'cornering' rides? 
Or are you not so concerned with this?


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## Migen21 (Oct 28, 2014)

I'm 6' 5"/245lbs. I run 25mm conti 4 seasons at 70f/75r for most rides. I never pinch flat. I've tried running higher pressure, and just can't stand the harsh feeling. The bike is a lot more 'connected' on the lower pressures, and it's a *lot* more comfortable to ride.

I might go up 5 or 10 psi in some circumstances, but I avoid it at all possible.


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## cxwrench (Nov 9, 2004)

duriel said:


> You guys seem to run your front tires a lot lower than the rear. When I do that and am going around corners, my fronts seem so spongy compared to the feeling I get from the rear. Also when standing the increased wt make them spongy again.
> Do you run more even pressure when under more difficult 'cornering' rides?
> Or are you not so concerned with this?


Never. It's in your head.


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## ToiletSiphon (Jul 23, 2014)

I get that it's way more comfortable to run at those low pressures and that there is no real risk of pinch flat. But from what I've read, the rolling resistance increases progressively (check out the bicycle tires rolling resistance website). I'm already used to the harsh feeling, but I don't want to be slowed downy. 

Envoyé de mon XT1563 en utilisant Tapatalk


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## dcgriz (Feb 13, 2011)

ToiletSiphon said:


> I get that it's way more comfortable to run at those low pressures and that there is no real risk of pinch flat. But from what *I've read, the rolling resistance increases progressively* (check out the bicycle tires rolling resistance website). I'm already used to the harsh feeling, *but I don't want to be slowed downy*.
> 
> Envoyé de mon XT1563 en utilisant Tapatalk


You are on chapter 1; go back and read the next 3 chapters to understand the whole story and not just part of it.


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## Jay Strongbow (May 8, 2010)

duriel said:


> You guys seem to run your front tires a lot lower than the rear. When I do that and am going around corners, my fronts seem so spongy compared to the feeling I get from the rear. Also when standing the increased wt make them spongy again.
> *Do you run more even pressure when under more difficult 'cornering' rides?*
> Or are you not so concerned with this?


No, that would be stupid.. I'd use LESS pressure if I know a certain ride will have much more difficult cornering than a typical ride. Why would someone reduce traction for cornering?


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## TJay74 (Sep 9, 2012)

190ish race weight, I run Vittoria Rubino Pro Speed 700x25 and run 90f/95-100r. Never pinched flat in all the years I have been riding, had one sticker flat last season. As Cxwrench said, I am always watching the road to make sure to miss any debris that can cause issues.


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## Lombard (May 8, 2014)

ToiletSiphon said:


> I get that it's way more comfortable to run at those low pressures and that there is no real risk of pinch flat. But from what I've read, the rolling resistance increases progressively (check out the bicycle tires rolling resistance website). I'm already used to the harsh feeling, but I don't want to be slowed downy.
> 
> Envoyé de mon XT1563 en utilisant Tapatalk


You may want to use this as a starting point. They use the 15% drop method:

Bicycle tire pressure calculator 

Use the 2nd box and enter your total weight (fully clothed ride, bike, water bottles and anything else on your bike) and your front and rear tire width.

It is a myth that greater pressures always equal less rolling resistance. That only works up to a certain point and only applies to hysteresis losses. However, just the opposite applies to suspension losses. In other words, in the real world of road cycling, roads are not perfectly smooth. So the more you are bouncing up and down, the more energy is wasted. That energy that could be propelling you forward is wasted in up and down motions. So getting the most efficient pressure is a balancing act. It is not a matter of more is better.

Also, as others here have mentioned, you would have to have much lower pressures to be pinch flat prone under normal riding conditions. If you hit a pothole of a size that will give you a pinch flat using these normal pressure guidelines, the pinch flat will probably be the least of your worries as you find yourself eating the pavement.

Also keep in mind the other benefits of lower pressures. As you already acknowledged, you have a more comfortable ride. The other thing you will have is better control and less chance of an accident if/when you do hit rough objects.


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## Lombard (May 8, 2014)

duriel said:


> You guys seem to run your front tires a lot lower than the rear. When I do that and am going around corners, my fronts seem so spongy compared to the feeling I get from the rear. Also when standing the increased wt make them spongy again.
> Do you run more even pressure when under more difficult 'cornering' rides?
> Or are you not so concerned with this?



I can't speak for others, but I tend to run an even greater difference between front and rear than most. I usually run around 65 front/95 rear. Why?

1) Most of my rider weight is in the rear. As I tend to ride a more upright endurance position, there is more of a front/rear weight distribution differential than someone who rides a competitive race position.

2) The rear wheel is where all the drive forces are. The front is basically just along for the ride.

3) I find hand road vibrations way more annoying that arse road vibrations.

I can't say I have ever found my front "spongy" at 60PSI. I also rarely ever stand up while pedaling.


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## dcgriz (Feb 13, 2011)

Lombard said:


> You may want to use this as a starting point. They use the 15% drop method:
> 
> Bicycle tire pressure calculator
> 
> ...


Fixed it for you:

_It is a myth that greater pressures always equal _*higher speeds*.


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## Lombard (May 8, 2014)

dcgriz said:


> Fixed it for you:
> 
> _It is a myth that greater pressures always equal _*higher speeds*.



I stand corrected, DC.  

But isn't it correct that the reason greater pressures don't always equal higher speeds is because of suspension losses?


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## dcgriz (Feb 13, 2011)

Lombard said:


> I stand corrected, DC.
> 
> But isn't it correct that the reason greater pressures don't always equal higher speeds is because of suspension losses?


affirmative


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## ToiletSiphon (Jul 23, 2014)

dcgriz said:


> Fixed it for you:
> 
> _It is a myth that greater pressures always equal _*higher speeds*.


Am I reading the chart wrong? What I see on the first one is that RR decreases as pressure increases...


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## dcgriz (Feb 13, 2011)

ToiletSiphon said:


> Am I reading the chart wrong? What I see on the first one is that RR decreases as pressure increases...


You are reading the chart right but are making the wrong assumption equating rolling resistance with speed.


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## Mike T. (Feb 3, 2004)

Lombard said:


> I stand corrected, DC.
> 
> But isn't it correct that the reason greater pressures don't always equal higher speeds is because of suspension losses?


I'm no physicist but look at the differences between road racing pressures (<100psi> or so) and indoor board track racing pressures of around 200 psi using tubular tires. The only real difference is the roughness of average roads versus the baby's bum smoothness of a wooden board track. When I was training on an indoor track I used clinchers (150g Conti Supersonics) inflated to 130psi. I didn't feel the rim lips could stand much more. Can you imagine riding the local chip & seal road at 130psi?


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## Lombard (May 8, 2014)

ToiletSiphon said:


> Am I reading the chart wrong? What I see on the first one is that RR decreases as pressure increases...



That is technically correct. However, go back to my remarks in posts 17 and 20 about suspension losses to see why decreased rolling resistance doesn't necessarily equal faster.

DC Griz and Mike T. have summed it up well.


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## TmB123 (Feb 8, 2013)

Keep in mind that the max pressure stated on the sidewall of the tire may be well above the max pressure that the rim is designed for. In other words, don't pump your tire to 130 if the rim is only designed for 110 and this changes with the width of the tire too.


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