bikeman715

sreten , you don't know what you are talking about . Specialize and other company do know theirs safely limits . as other posted what you see on tire is half of that limit for errors to be make and the tire not to blow off . Different material in the tire will rate what that limit may be . if it 60 psi or 100 psi .

rootboy 

Could have been a defective tube. It happens.

sreten

Hi,

You don't know that. You choose to think that rather
than rationalise and analyse the information available.

I've a much better idea of what I'm talking about than
someone who assumes all numbers on tyres must be
correct, even when they wildly differ between numbers
that do make sense on most tyres and baffling numbers
on some tyres, that clearly don't mean the same thing
as the numbers they do make sense for most tyres.

rgds, sreten.

FBinNY 

I know I have language problems, but it sounds like your saying that anyone who believes the molded in pressure numbers that are beyond the range you think is correct are gullible fools (or something to that effect).

I don't know if the expression "you're all wet" means anything across the pond, but with all due respect, you couldn't be any wetter if you rode 100 miles in a steady downpour.

BTW- my commuter has 26x2.0 tires (not high end) rated to 85psi. That's effectively higher than a 47mm tire at 100. I have every confidence the tires could take the pressure, having dealt with this company for a number of years. But, then again, maybe I'm just gullible.

bikeman715

That the different between you and I , You going on limited information and you think you are right about it , which you are not . I on the other hand have 30 years of experience on the bike and around the bike doing sales and service . Maybe what you should do is do a little research on the subject before you post .

davidad

That little bit of info comes from the manufacturers to cover their asses.

sreten

Hi,

I doubt you have any language problems. But sometimes implication does not come across.
Not what I think (as an opinion) but general concensus about tyres and tyre pressures
suggests ranges for various sized tyres based simply on physics modified by details.

I would suggest anyone who seeks out tyres with numbers on them just to disagree
with me "is all wet" as they can't be arsed to work out what I'm actually on about.

Analysis of the min and max ratings of decent manufactures tyres are consistent
with the numbers meaning safe minimum pressure and safe maximum pressure
and nearly all sensible use of the tyre for all rider weights is encompassed.
(By keeping maximum low a wider tyre is encouraged for the heavier).

The Michelin City Road 622mm x 32mm on my road bike is rated to 85 psi.
Its not light at all, its heavish, strong, tough strong puncture protected tyre.

If your 2" tyres can really take the same pressure they will weigh far more
not only because they are bigger, but because they need to be built stronger.
Pointlessly, as they need far less maximum pressure than 32mm tyres.

Sensible ranges of tyres the min and max vary with the tyre size consistent
with the tyre being made the same but just varying width of construction.

Anything else makes no sense to me and I don't trust stupid numbers.

Trusting stupid numbers to mean the same as sensible numbers
is being gullible, most likely the numbers mean different things,
or they are made up by the marketing department who stupidly
think the minimum pressure has to be high to impress people.

rgds, sreten.

FBinNY 

You're right, I truly have no idea what you're on about, or think you're on about. But I'd love to see some evidence of this general consensus.

Not speaking about what pressures and tire widths make sense, but simply whether tires can handle rated pressures, I repeat my assertion that you're way of base.

The fact is that reputable tire makers do not lie, when they mold pressure ratings into tires. They leave large safety margins, to cover manufacturing tolerance, temperature, and riding conditions, including a reserve for aging, since the tire has to meet it's rating, not only when new, but throughout it's predicted service life.

The rating covers two things.

1- blow off pressure, which is determined by the tensile strength of the bead, combined with the action of the interlock between the tire and rim hooks (if any).
2- burst pressure (or wall integrity) which is determined by the strength of the fabric plies.

ALL tires will comfortably handle pressures well beyond the rated pressures (on the right rim) and tire companies have ongoing testing to make sure they meet whatever the reserve the maker feels is necessary. I'm not sure it's a 100% reserve, but it's not a small margin either.

Your assertion that tires strong enough to handle high pressure in a large section, shows that you have no idea of what makes tires heavy, which is mostly the non-structural rubber. Beads aren't a major contributor, even steel beads, and the structural walls aren't either benefiting from improvements in materials, including better cotton threads, plus polyesters and aramids.

So the reality is that with quality materials and production methods it's very possible to produce high quality, reasonably light, high pressure tires in wide sections. I'd go so far as to venture that the upper limits aren't technical but market need, and rim strength.

sreten

Hi,

People here are so argumentative that they seem to be blinkered
as to what they actually agree about (which covers most things)
and what they disagree about which is the details.

Anyone saying I'm way off base there is no point continuing.

For example :

"Your assertion that tires strong enough to handle high pressure in a large section, shows
that you have no idea of what makes tires heavy, which is mostly the non-structural rubber."

Is entirely inconsistent with what I've already said, which implied
any difference beyond the extra rubber needed for the tyre size
and as such any extra weight required for the extra strength.

rgds, sreten.

Generally for a give size range of tyres the beads and walls don't change,
weight is related to tyre size and not strength as I previously implied,
and maximum pressure drops the the bigger the tyre width is, the
numbers consistent with consistent maximum bead / wall forces.

FBinNY 

Things have been getting stronger without weight increases for over a century. Bike are lighter yet as strong (some are lighter yet not as strong, but that doesn't contradict the first part). Tires also benefit from improvements in materials which are pound for pound much stronger than before.

In any case, as I said most of the weight is non-structural, namely the rubber. So it's very possible to build a tire with stronger structure with only a marginal (if any) weight penalty.

So you already got the break you're asking for, more stuff makes tires heavier, but stronger stuff doesn't. That's not nothing.

I've gone about as far as manners and BF policy allows me, so I'll just put it to you.

You assert that manufacturers lie about pressure ratings. If you have any evidence at all, of any kind, not might be the time to offer it, or apologize to all the tire makers and withdraw your assertion. (no need to apologize to me, since I don't make tires. But I do produce products, and make claims, so I'm sensitive to unsupported claims that producers lie.

boattail71

Gotta say some of you are being harsh on sreten. I'm kinda in agreement with him. That my 38mm (1.5s) might physically take 100 psi, well, it just doesn't seem right - in my decades of riding all kinds of bikes and tire sizes, yes tire technology has improved but jebus! 100 psi in a 47mm? Just doesn't seem right.

FBinNY 

Doesn't seem right, isn't a basis for asserting that it's not possible, or for accusing folks or putting false pressure ratings onto their tires.

As I said, I'm not debating whether it makes practical sense for riding, that's another story. But I have absolute faith that it's very possible to built quality 47mm tires that will hold 100psi plus a reserve.

I'll go farther and say the limit isn't in the tires but in what rim flanges will take. When I visited a tire factory's testing room, I saw that testing was done on massive steel discs (aka rims) with flanges at least quadruple the strength bicycle rims. Tires were taken to burst or blow off, and the technicians noted the mode of failure, and the pressure. I might add that they stood in another room to protect their ears, and themselves from rubber shrapnel.

sreten

Hi,

No. I've asserted that some numbers on tyres don't mean the same thing as the numbers
that European manufactures seemed to have settled on (possibly from fear of law suits).

There is no need to lie when you can use whatever criteria you want, you can mislead.

I've never asserted pressure ratings on tyres are all wrong, just that some are a joke.

You won't find any 47mm European tyre rated at 100 psi (for bicycles).

A 28mm tyre rated 115psi to 125psi means what ? A safe minimum to a safe
maximum ? Not a chance and an utterly stupid range to put on the sidewall.
Whatever its supposed to mean Specialized don't bother to explain.

rgds, sreten.

As I said I'll take on even money a 47mm bicycle tyre not
getting to 200psi I simply can't lose in the long run ...

chrisabn

The tires can probably take boatloads of psi without a doubt...but it's the tube that I blew up. And if my common sense does not fail me, tubes are a lot weaker than tires.

FBinNY 

Here's a link to a pair of Kenda 40-559 tires that aren't particularly high end. Note that they offer a normal pressure, and a newer HP version rated to 100psi. They charge a bit more for the HP version, which you'll also note is actually a bit lighter.

I've never been an advocate of extremely high pressures, never felt a need to go beyond 105psi on 25mm tubulars, and ride my 50mm commuter tires at 60/50, but we have to separate what makes sense for any particular rider, from the assertion that large section HP tires cannot be made, and in this case at least, fairly inexpensively.

ThermionicScott 

At the risk of derailing a perfectly fine debate over the meaning of tire ratings, it's possible that a little bit of the tube got pinched under one of the tire beads, found its opportunity to blow, and then retracted into the tire after it blew. The long rip in the tube is evidence that the tube had good exposure to the outside world for an instant.

I've found it's good practice to put a little air into the tube before installing the second bead. Not much, just enough to give the tube some shape, but it's usually enough to get it out of the way. Once the second bead is on, work your way around the tire, pressing in on the side to make sure the tube isn't poking out from behind the sidewall. Put a little more air in the tube and make sure the tire is evenly seated all the way around. You can push and pull on it to even things out. Then, bring it the rest of the way up to your desired pressure, keeping an eye on it as you go. That was a bunch of words, but it becomes second-nature after a couple of tire changes and all but guarantees you won't have another blow off.

FBinNY 

Tubes can withstand up to about 3psi. As explained early on, it's the tire and rim that form a closed chamber of fixed dimensions. The tube inflates until it presses against the inner wall of that chamber then has no place else to go. If the tube blew up, it's because there was an opening for it to blow into.

sreten

Hi,


I still maintain silly numbers on the side of a tyre indicate
whatever the numbers mean they don't mean what typical
numbers mean. 75psi min is just very silly for a 47mm tyre.

Why some tyres have silly numbers is beyond me, they
will only confuse and cause general misuse of the tyres.

There are still people who simply pump up both tyres to the
maximum stated on the sidewall, no real idea about pressures.

Regarding :

https://www.modernbike.com/itemgroup....FRKe4Aod-FEAlA

Just proves the myth of high pressures ratings = a better tyre
lives on, and as long as it does products will pander to it.

The pump to the max brigade most of the time for a 1.5"
tyre would be better off with the 65 psi version over 100psi.

rgds, sreten.

I run my tyres on based on 10% to 15% drop based
entirely (sorry) on the physics of the tyre size and
my weight and the bikes weight distribution and
some empirical experience of the best pressures.
The tyre details suggest lower or higher drop.

bikeman715

Not always, it depends on rider , weight, road condition, weather ,and so on . I don't see your point you keep trying to show about PSI because you don't understand it as with your limited understanding of it or cycling for that matter . Different PSI will affect the handling of the bike , no matter if it high or low . So sretent please do some research on subjects before you post and start arguments here it would help you and others who will read your posts .

sreten

Hi,

There is no regulation, the numbers can mean whatever the manufacturers want.

However according to Sheldon Brown lying about tyre sizes used to be rife,
with the excuse everyone else is doing it, so we do to be able to compete.

Whatever, IMO you can't trust the the two numbers on a tyre to mean
the same thing on all tyres, if you insist they do, your very gullible.

rgds, sreten.

GuyWood

I had a specialized Fatboy at 90 odd PSI blow off the rim of my MTB as I was riding along a few years ago. Spare inner tube? I nearly needed new underpants . I think what happens is the bead is blown off the rim by the excessive pressure and the air in the tube blows a massive hole in the inner tube as it exits through the hole left by the bead coming over the edge of the rim.

sreten

Hi,

Meandering waffle means to me you don't know what your talking about, not me.
So please don't try and make out I know less than the little you apparently do.

rgds, sreten.

bikeman715

+1 GuyWood , that how it happen , may the bead and/or rim can be damage for it to happen or any other reason for the bead to slip off the rim .

bikeman715

I do know more than you do about cycling and repairs . How dare you say that about me .Go and read a book maybe that you will learn something other that argue a pointless point about PSI and tires .

Al1943

The most useful post on this thread!