Correct Tire Pressure?

"Mark Williams" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I have tried to search the web and look through the old news group threads,
but am still not sure the range of tire pressure I should try. I am road
bike rider and do long distance road riding. I weigh 135 pounds. The
tire I am using is a Vittoria Open Corsa EVO CX 700X23c. This tire has a
max of 145 psi, but I have been running them at 105 psi in the back and 95
in the front. A person that I was riding with this weekend was telling
me you should always put the max in to get the least amount of rolling
resistance. I am hoping to get a better understanding from this group on
the best tire pressure to use... that provides a balance between
performance and comfort. Is there an equation that provides a good starting
point to work from? Recommendation and thoughts are very appreciated!

Why would you not want to go with the manufacturers' recommendation?

Quoted message said:

I have tried to search the web and look through the old news group threads,
but am still not sure the range of tire pressure I should try. I am road
bike rider and do long distance road riding. I weigh 135 pounds. The
tire I am using is a Vittoria Open Corsa EVO CX 700X23c. This tire has a
max of 145 psi, but I have been running them at 105 psi in the back and 95
in the front. A person that I was riding with this weekend was telling
me you should always put the max in to get the least amount of rolling
resistance. I am hoping to get a better understanding from this group on
the best tire pressure to use... that provides a balance between
performance and comfort. Is there an equation that provides a good starting
point to work from? Recommendation and thoughts are very appreciated!

In general I also recommend max rated pressure, but not always. You're
pretty light for one thing, and that 145psi is *awfully* high for a 23c
tire. Most 23c tires recommend 115-120psi, which should be more than
adequate to prevent compression cuts and also high enough to provide very
low rolling resistance. At 145psi, I'd wonder if you might be losing
traction on anything but the smoothest of road surfaces.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

Raoul Duke said:

"Mark Williams" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I have tried to search the web and look through the old news group
threads, but am still not sure the range of tire pressure I should
try. I am road bike rider and do long distance road riding. I
weigh 135 pounds. The tire I am using is a Vittoria Open Corsa EVO
CX 700X23c. This tire has a max of 145 psi, but I have been
running them at 105 psi in the back and 95 in the front. A person
that I was riding with this weekend was telling me you should always
put the max in to get the least amount of rolling resistance. I am
hoping to get a better understanding from this group on the best
tire pressure to use... that provides a balance between performance
and comfort. Is there an equation that provides a good starting
point to work from? Recommendation and thoughts are very
appreciated!

Why would you not want to go with the manufacturers' recommendation?

The 145 psi is a MAX recommendation -- and an unusually high one at that (?)
I would think. The tires doubtless have a recommended RANGE on the
sidewalls, and the OP, being so light, should likely start on the low end of
that.

A veteran roadie friend of mine said something about a 15% "sag" (the amount
the tire casing compresses) being ideal for overall performance (grip,
rolling and flat resistance, etc.), but I can't quite bring myself to run
'em that "soft" (or what/ seems/ soft to me). I generally run the rear at
close to manufacturer's max, and the front around 10 psi less -- but I weigh
175-180, not 135.

If Mark (OP) is happy with the way the tires ride now, why change?
Experiment a bit, perhaps, but if it ain't broke...

Bill S.

Mark Williams said:

I have tried to search the web and look through the old news group threads,
but am still not sure the range of tire pressure I should try. I am road
bike rider and do long distance road riding. I weigh 135 pounds. The tire
I am using is a Vittoria Open Corsa EVO CX 700X23c. This tire has a max of
145 psi, but I have been running them at 105 psi in the back and 95 in the
front. A person that I was riding with this weekend was telling me you
should always put the max in to get the least amount of rolling resistance.
I am hoping to get a better understanding from this group on the best tire
pressure to use... that provides a balance between performance and comfort.
Is there an equation that provides a good starting point to work from?
Recommendation and thoughts are very appreciated!

Most people run max or near-max pressures on the road but there's no
reason you must. An inflation pressure that limits the tire's
deformation under the rider's weight to a minimum will result in lower
rolling resistance but pressure is only half of that combination. The
other half is the rider's weight. At 135 lbs, your weight may very well
deform the tire less at 105 lbs psi than a 180 lb rider's weight might
at 145 lbs psi. A good starting point might be to inflate the tires
just enough to avoid pinch flats and then increase it incrementally
until the ride becomes too rough. Decrease the pressure until you reach
a happy medium.

Regards,
Bob Hunt

"Sorni" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

The 145 psi is a MAX recommendation -- and an unusually high one at that
(?) I would think. The tires doubtless have a recommended RANGE on the
sidewalls, and the OP, being so light, should likely start on the low end
of that.

I realize 145 psi is a MAX recommendation. I was merely curious why the OP
would not want to go with the recommended pressures, which are no doubt
clearly printed on the sidewalls, and decide to make up his own. It seems
unlikely that the recommended range would be between 95-145 psi.

"Raoul Duke" <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

I realize 145 psi is a MAX recommendation. I was merely curious why the
OP would not want to go with the recommended pressures, which are no
doubt clearly printed on the sidewalls, and decide to make up his own.

That is false. Some manufacturers (e.g., Michelin) do have recommendations
on their web site (based on the rider's weight), but they are not printed on
the tires.

A tire tread has a certain durometer hardness, which does not change as the
tire pressure is increased. At very high pressures, wouldn't one expect the
behavior and feel of the tire to be controlled mainly by the tread
properties?

Ken said:

"Raoul Duke" <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

I realize 145 psi is a MAX recommendation. I was merely curious why
the OP would not want to go with the recommended pressures, which
are no doubt clearly printed on the sidewalls, and decide to make up
his own.

That is false. Some manufacturers (e.g., Michelin) do have
recommendations on their web site (based on the rider's weight), but
they are not printed on the tires.

That is false. (Not categorically but I like the ring of it 🙂

My Michelin Pro Race 2s have the range printed on the tires -- smallish
print and only on one side, but it's there.

Bill "8 bar max seems low though" S.

Leo Lichtman said:

A tire tread has a certain durometer hardness, which does not change as the
tire pressure is increased. At very high pressures, wouldn't one expect the
behavior and feel of the tire to be controlled mainly by the tread
properties?

It's true that the degree of inflation doesn't change the rubber
compound but the amount of rubber actually contacting the roadway- a
tire's "footprint"- depends entirely on the combination of rider weight
and tire pressure. In terms of cornering ability, the size of the
footprint is at least as important as the relative hardness or softness
of the rubber compound while ride comfort depends almost exclusively on
inflation pressure. As far as the tread *pattern* is concerned, on most
23mm road tires (not MTB knobbies and excluding studded snow tires)
that tread pattern is either non-existent or almost so.

Regards,
Bob Hunt

Raoul Duke said:

It seems unlikely that the recommended range would be between 95-145 psi.

Not at all, regardless of what it says on the sidewall. It all depends
on the weight of the rider. For a lightweight rider 95 psi (about 6.5
bar) is perfectly reasonable and commonly used with a 23-mm tyre.
However, a significantly heavier rider would need significantly higher
pressure for the tyre to perform similarly and to avoid pinch flats.

-as

"Bob" wrote: (clip) a tire's "footprint"- depends entirely on the
combination of rider weight and tire pressure.
^^^^^^^^^^^^^^^
Just as a "thought experiment": suppose you had a tire with a solid steel
inner tube. That would be equivalent to an inner tube with infinite air
pressure. The footprint would depend entirely on the weight of the rider
and the characteristics of the rubber--durometer hardness, thickness, tread
pattern, roundness. Now substitute an inner tube with very high air
pressure, and I don't expect the pattern would change appreciably. Now
picture what happens to the footprint as the pressure is lowered. I'm
guessing that somewhere below 200 psi you would begin to get noticeable
changes, and down around 100 psi you would be dealing with a normal
footprint, due partially to the rubber, and partially to the air.

So, my question is: at pressures over 100 psi, do differences really matter
much?

Another consideration is that as you increase the pressure, you become
somewhat more likely to experience punctures. 110 lbs. should be
plenty for such a light rider.

Leo Lichtman said:

"Bob" wrote: (clip) a tire's "footprint"- depends entirely on the
combination of rider weight and tire pressure.
^^^^^^^^^^^^^^^
Just as a "thought experiment": suppose you had a tire with a solid steel
inner tube. That would be equivalent to an inner tube with infinite air
pressure. The footprint would depend entirely on the weight of the rider
and the characteristics of the rubber--durometer hardness, thickness, tread
pattern, roundness. Now substitute an inner tube with very high air
pressure, and I don't expect the pattern would change appreciably. Now
picture what happens to the footprint as the pressure is lowered. I'm
guessing that somewhere below 200 psi you would begin to get noticeable
changes, and down around 100 psi you would be dealing with a normal
footprint, due partially to the rubber, and partially to the air.

So, my question is: at pressures over 100 psi, do differences really matter
much?

In a word, yes, because in terms of footprint size the weight of the
load is much more important than the tire compound's physical
characteristics.
On my bike at my usual late spring/early summer weight of 135ish, a
tire pressure of 110 lbs psi results in a firm but comfortable ride.
That same pressure on a late season ride when I'm anywhere between 6 to
10 lbs lighter, results in a rather harsh ride. 130 lbs psi in the
early spring gives me the same harsh type of ride. In the late summer
130 lbs psi is rough as hell and actually decreases my cornering
ability because the slightest little bump in the road can cause my
wheel to leave the pavement.
So much for one word answers, eh? ;-)

Regards,
Bob Hunt

Mark Williams said:

I have tried to search the web and look through the old news group threads,
but am still not sure the range of tire pressure I should try. I am road
bike rider and do long distance road riding. I weigh 135 pounds. The tire
I am using is a Vittoria Open Corsa EVO CX 700X23c. This tire has a max of
145 psi, but I have been running them at 105 psi in the back and 95 in the
front. A person that I was riding with this weekend was telling me you
should always put the max in to get the least amount of rolling resistance.
I am hoping to get a better understanding from this group on the best tire
pressure to use... that provides a balance between performance and comfort.
Is there an equation that provides a good starting point to work from?
Recommendation and thoughts are very appreciated!

If the pressures you are using have consistently produced good
results, I say there's nothing to fiddle with.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Quoted message said:

Quoted message said:

I have tried to search the web and look through the old news group
threads,
but am still not sure the range of tire pressure I should try. I am road
bike rider and do long distance road riding. I weigh 135 pounds. The
tire
I am using is a Vittoria Open Corsa EVO CX 700X23c. This tire has a max
of
145 psi, but I have been running them at 105 psi in the back and 95 in the
front. A person that I was riding with this weekend was telling me you
should always put the max in to get the least amount of rolling
resistance.
I am hoping to get a better understanding from this group on the best tire
pressure to use... that provides a balance between performance and
comfort.
Is there an equation that provides a good starting point to work from?
Recommendation and thoughts are very appreciated!

If the pressures you are using have consistently produced good
results, I say there's nothing to fiddle with.

The question just got more interesting... today I purchased a new set of
Vittoria Open Corsa EVO CX 700X23c. I came to realize that the Vittoria
Open Corsa CX on my bike was a previous version. The early version
indicates 7/9 bar or 100/130 psi. The new version now indicates 8/10 bar
or 115/145 psi. It looks like what I was running them was right around
the minimum. Since the new tires range is higher, do I need to be at
least around 115 psi?

Thanks to everyone for all your thoughts!

Quoted message said:

--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Sorry, I forgot to include the URL for Alfred E. Bike. It's
http://aebike.com/index.cfm

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Another consideration is that as you increase the pressure, you become
somewhat more likely to experience punctures. 110 lbs. should be
plenty for such a light rider.