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max tire pressure...do you go over.(16 posts)

max tire pressure...do you go over.ishmael
Apr 25, 2002 5:42 AM
i know its been discussed but so has everything and i forget the outcome so its exciting to me once again, the pleasures of a bad memmory...i have a friend who says he always looks at the max tire pressure allowed and then puts atleast 30 more pounds in....that sounds scary but i like to go over by 5 or so...by the way if you like pressure panaracer pro tires do 150 and they are about as light as equivalent weight conti and michelin, havent put them on yet but theyre sitting in the box and waiting
Overpressurization is crazy...eschelon
Apr 25, 2002 5:54 AM
I like you will usually go over by 5, but 30?...I know that in most cases, nothing serious may happen, but I had my tire explode on me...not while riding, but while I was seated on a curb next to my bike...the explosion was so loud that my ears were ringing real bad for a few minutes.
high pressure is over blownDougSloan
Apr 25, 2002 5:55 AM
I usually put in around 5-10 over label, depending upon the tire. I have some tubulars that can handle 215 psi that I run at 130, though.

Depends upon what you are doing. For a very long ride on bumpy roads, where comfort matters, I'd probably go with much less, say about 115. For a 10 mile time trial on smooth roads, maybe 160.

Beware, I have had Conti Supersonics blow off the rims and pressures below the label maximum. That's bad.

Excess pressure won't necessarily make you faster. At some point, you just start bouncing all over the pavement, plus your contact patch is reduced enough to affect cornering ability.

Air pressure, I believe, is the single largest factor in a bike's comfort. You can make any bike harsh or relatively comfortable with about a 20-30 psi variance.
re: marketing vs liabilitycyclopathic
Apr 25, 2002 6:06 AM
the max pressure on tires is "incidental", there're several reasons why it may be too low or too high. First it starts with the actual tire construction and materials used. Then the lawyers look at it and they wanna push it lower because if it blows off the rim you're liable. Then marketing comes and though they generally wanna push it higher to compete against other brands they will probably push it down on cheaper tires to make high end offering look more appealing.

but let's look at the risks. Chances of blowing clincher off rim also depend on rim used, so 150psi may be too much on one or o'k on other. I suspect 50-60psi is the safety margin, I wouldn't trust tire designed for 120psi with 170.

Since studies had shown there's very little benefit of putting more then 110-130psi, there's no reason to go much higher IMHO
So what's the pressure rating on your rim?Spoke Wrench
Apr 25, 2002 6:11 AM
A tire with a 150psi rateing won't do anything to make your rim any stronger. If you do a search, I don't think you will have too much trouble finding manufacturers who have had histories of bicycle tires blowing off rims. I can think of two just off the top of my head, so I assume there's got to be a lot more. I'm a lot more conservative about tire pressure than I was 10 years ago.
So what's the pressure rating on your rim?Chen2
Apr 25, 2002 6:24 AM
Good point on rims. My wife's Mavic Helium wheels when new came with a big printed warning that the rims were limited to 110 psi. Mavic later retracted that warning and put a 135 psi (I think) rating on them, I suspect the change in rating had more to do with marketing than engineering. As I understand it, the Helium rim is basically the same as the Open Pro. At 135 psi there is probably still a safety margin, but who knows how much? I run my Axial Pro's at ~118 - 120 psi. I noticed that the recommended limit on those tires has been raised to 115. In general I think heavier riders should carry more air pressure than lighter riders, but within reasonable limits.
~Al
No, I try to remain safe and comfortable.Quack
Apr 25, 2002 6:14 AM
Even though your tires may be rated as 150psi capable, your rim may not be rated to hold it. As an example, the typical Mavic Open Pro with 700-23 tires is rated about 140psi. You could crank them past that, but I wouldn't trust the setup descending some gnarly broken asphalt at high speed. If you happen to suffer an impact at these pressures, your bead can blow off or even worse, your rim could crack and send you flying. I've found that 120psi is the magic number for me. It's the perfect compromise between resistance, comfort, and durability for my 145lb body on a carbon frame.
No, I try to remain safe and comfortable.No_sprint
Apr 25, 2002 6:17 AM
I too like the 120 number for most clincher setups.
the rating on the conti grand prix have gone up 30psiishmael
Apr 25, 2002 6:40 AM
ive got one on my bike that i bought about 3 years ago and its rating is 150, i see them sold now with a 120 or something rating...so generally all the tires out there are just as safe at pressure its just an arbitrary number made by the company? sometimes i get a tire thats got a really tight bead, id imagine that would be safer(makes me feel better atleast)...what would be a safer tire at high pressure
I've got a set of the Panaracers.Gregory Taylor
Apr 25, 2002 6:46 AM
If you look, they recommend 100 lbs. of air, even though the tire is rated to 145-150. I'll crank it up to 120 for a fast Sunday ride, but most of the time I'll use the recommended 100. I did pump them up to 145 once, and it was like riding a pogo stick. The higher pressure doesn't yield that much of a reduction in rolling resistance, and they are much more comfortable at 100.

Great tires, by the way.
i notice huge differences in rolling resistanceishmael
Apr 25, 2002 6:50 AM
between 100 and 150...my ass and hands are never sore also...
Hmmm....what tires are you running now?Gregory Taylor
Apr 25, 2002 7:03 AM
I could see you feeling a difference if you increased the pressure from 100lbs. to 150lbs. But does the tire truly have less rolling resistance? Or does it just feel faster with more pressure in the tire? I'm sure that there is a study out there somewhere that can quantify all of this...

Bottom line is that if you are comfortable, and the tires and rim are rated to take the high pressure, then go for it.

Glad to hear that you have a pain-free posterior.
i wouldve thought pressure was more important than brandishmael
Apr 25, 2002 8:00 AM
and the more pressure the better as long as the surface was smooth..even on tight turns id think it would be better, yes there would be a smaller contact patch but the pressure on that patch would do the sticking work...low pressure tires slide on turns so id imagine that the opposite would be true with more pressure and the harder the tire the better..
My question about what brand you were currently riding...Gregory Taylor
Apr 25, 2002 9:23 AM
...was aimed at seeing whether the difference between your experience and my experience could be explained by differences in tire construction. There are a lot of things that affect a tire's feel -- things like casing construction, rubber compound, cross section, etc.
i use max pressureColnagoFE
Apr 25, 2002 7:10 AM
for my contis which is about 120psi but then again i weigh 195. If I was a "normal" weight I'd probably back it off a bit. I'd never go over by 30 lbs...sounds like a blowout waiting to happen.
I always run 130 psi...Ron B
Apr 25, 2002 7:49 PM
but I do it more to keep from getting pinch flats. I weigh 260 pounds and at lower tire pressures I get way to many pinch flats.

I've never had a tire blow out on me and I generally ride around 3K - 4K a year.