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saturnsc2 08-10-05 02:22 PM

armadillo tire pressure
 
do a lot of you use ARMADILLO ALL CONDITION tires here? they are awesome tires & are supposed to be very flat resistant. i just installed a set of these on my road bike. they are 27 x 1 1/4. the tire pressures are as follows on the tire: 115 minimum, & 125 maximum. is it critical that i maintain such a high pressure? i mean, will the tires be damaged if i ride them underflated? the last thing i want to do is damage these expensive kevlar lined tires. when i inflate them at half that pressure they are still pretty firm & i wonder why they have to be inflated so high. since bike tires seem top lose air when not in use, i would imagine that it will be a task to keep up that high pressure all the time & they will be frequently used underflated...

slvoid 08-10-05 02:52 PM

Most of that is just an average number for "optimal" performance.
Cept if it's bumpy, you might actually get better performance with lower pressure. My inifiniti's are rated at min 75psi max 90psi. Yet it works best right around 65psi on the rough city roads. When the roads are smooth, 90 does the trick.

I usually top off my weekend bike's 700x23 tires before every ride if it's been sitting there more than a week or every 2 rides. My commuter's 700x35's get topped out at around 75-80 psi every 2 weeks.

You don't want it too high that it's really rough but not too low that it's pinching either.

77Univega 08-10-05 08:15 PM

Quote:

Originally Posted by saturnsc2
do a lot of you use ARMADILLO ALL CONDITION tires here? they are awesome tires & are supposed to be very flat resistant. i just installed a set of these on my road bike. they are 27 x 1 1/4. the tire pressures are as follows on the tire: 115 minimum, & 125 maximum. is it critical that i maintain such a high pressure? i mean, will the tires be damaged if i ride them underflated? the last thing i want to do is damage these expensive kevlar lined tires. when i inflate them at half that pressure they are still pretty firm & i wonder why they have to be inflated so high. since bike tires seem top lose air when not in use, i would imagine that it will be a task to keep up that high pressure all the time & they will be frequently used underflated...

--- Funny you should ask. I happen to have those very tires on my '70's road bike which has straight sided rims. Found out that those high pressure tires are made for hook bead rims. So after I had my FIRST blow off (at 115 psi), I have been inflating them to 95 psi. No problems since then.

saturnsc2 08-10-05 09:54 PM

Quote:

Originally Posted by 77Univega
--- Funny you should ask. I happen to have those very tires on my '70's road bike which has straight sided rims. Found out that those high pressure tires are made for hook bead rims. So after I had my FIRST blow off (at 115 psi), I have been inflating them to 95 psi. No problems since then.

when you say "hook bead" rims are you referring to a rim that has a little lip on the inside of the rim just below the edge? if so that's what i got. my rear rim is a sun double wall rim, & the front is a older wider single wall rim. both are an aluminum alloy with that lip on the inside. how long did it take until your tire blew off? i would imagine right away eh? i didn't realize that they even made rims without that lip. what holds the tires on a kind of rim with a straight edge?

dee-vee 08-10-05 10:32 PM

I have the 700*28 all condition armadillo on my commuter and I keep them at 100psi but they fall down to around 70psi after a week or so. I should start airing them up more often. The back tire seems to lose air faster than the front too.

77Univega 08-10-05 10:39 PM

Quote:

Originally Posted by saturnsc2
when you say "hook bead" rims are you referring to a rim that has a little lip on the inside of the rim just below the edge? if so that's what i got. my rear rim is a sun double wall rim, & the front is a older wider single wall rim. both are an aluminum alloy with that lip on the inside. how long did it take until your tire blew off? i would imagine right away eh? i didn't realize that they even made rims without that lip. what holds the tires on a kind of rim with a straight edge?

--- Yes, the "hook bead" or "hook edge" rims have the lip on the inside. Actually, I rode on those tires for a couple months at 115 psi before the blow-off. Those straight-sided rims were made back when typical road tire pressures were only ~ 75 psi.
After I learned the HARD way about rims, I finally consulted the guru, Sheldon Brown's glossary at:
www.sheldonbrown.com/gloss_h.html
Thus spake Sheldon:
"Hook Edge Rims
A rim with a ridge on the inner edge to help retain the bead of a clincher tire. Some older rims were straight-sided, and will not hold a tire as securely as a hook-edge rim (that is, the tire cannot be inflated to as high a pressure.) Virtually all good quality rims in current production are of the hook-edge type."

Lucky for me, the blow-off did not occur on the road. It happened about 20 minutes after I had parked the bicycle in the church meeting hall. It suddenly went off with a loud BANG. We first thought it was the coffee pot blew up! Hahahaha

lilHinault 08-10-05 10:46 PM

I keep my tires at 80 psi, I'm not that heavy a rider and I look at it in terms of tire deformation - you want the tire to deform a little bit as you ride, that's the cushioning effect of inflatable tires. But, you don't want to risk pinch flats, tire "walking" on the rim, etc by underinflation. 80 PSI seems to work for me.

Nicodemus 08-11-05 05:30 AM

I have the Armadillo All Condition tyres. Crikey, I can't imagine running them at the recommended pressure. I usually keep mine at about 60-70 psi. Any higher than 80 and the ride's way too harsh.

I'm sure a lot of it will have to do with your riding surface and bicycle. For me, an aluminium frame and carbon forks make the bike quite rigid, so I really feel it if the tyres are hard.

saturnsc2 08-11-05 06:32 AM

Quote:

Originally Posted by Nicodemus
I have the Armadillo All Condition tyres. Crikey, I can't imagine running them at the recommended pressure. I usually keep mine at about 60-70 psi. Any higher than 80 and the ride's way too harsh.

I'm sure a lot of it will have to do with your riding surface and bicycle. For me, an aluminium frame and carbon forks make the bike quite rigid, so I really feel it if the tyres are hard.

i guess you can get away with that if you are an exceptionally light rider. i think i just better use the recommended pressure. the ride is harder than my old tires, but i use a wide gel filled seat & can't feel the stiffer ride. i just feel it through the handlebars, but if you want flat resistant tires, then you have to sacrifice some ride softness for the harder tires.....

saturnsc2 08-11-05 06:36 AM

Quote:

Originally Posted by 77Univega
--- Yes, the "hook bead" or "hook edge" rims have the lip on the inside. Actually, I rode on those tires for a couple months at 115 psi before the blow-off. Those straight-sided rims were made back when typical road tire pressures were only ~ 75 psi.
After I learned the HARD way about rims, I finally consulted the guru, Sheldon Brown's glossary at:
www.sheldonbrown.com/gloss_h.html
Thus spake Sheldon:
"Hook Edge Rims
A rim with a ridge on the inner edge to help retain the bead of a clincher tire. Some older rims were straight-sided, and will not hold a tire as securely as a hook-edge rim (that is, the tire cannot be inflated to as high a pressure.) Virtually all good quality rims in current production are of the hook-edge type."

Lucky for me, the blow-off did not occur on the road. It happened about 20 minutes after I had parked the bicycle in the church meeting hall. It suddenly went off with a loud BANG. We first thought it was the coffee pot blew up! Hahahaha

i never seen a rim without that lip in it. the rims you must have had were pretty old. i guess if the pressure is very low, they will stay on the rims without the bead. i'm surprised you got to ride that long without any problems. these tires are likie rolling bombs on my bike with all that pressure. if one ever blew out, i'm sure you would hear it for miles! my road bike is a 1982, & even back then i remember rims still having that lip. of course my rims were replaced & are not original. as a matter of fact, the rear rim is brand new replaced a 2nd time.

saturnsc2 08-11-05 06:42 AM

Quote:

Originally Posted by dee-vee
I have the 700*28 all condition armadillo on my commuter and I keep them at 100psi but they fall down to around 70psi after a week or so. I should start airing them up more often. The back tire seems to lose air faster than the front too.

ya that's what i figured. my old 90 psi tires needed re-filling up every 2-3 weeks, but these will lose air faster because of the higher pressure. i have a good pump with a pressure guage on it. i guess i will have to check the pressure more often. hell, it's better than fixing flats right? i wonder where the air gets out. no visible leaks anywhere when i do the water test. there's been many threads here about how air escapes from the tire, but nobody seems to have any hard facts just opinions...

cedo 08-11-05 11:32 AM

Quote:

Originally Posted by slvoid
Most of that is just an average number for "optimal" performance.

It would seem to me that based on total weight (bike + rider) and the width of the tire, you should be able to scientifically devise a tire pressure chart that provides optimal "deflection." I have found one source although whenever I have shown it to an LBS, they criticize it for being wrong, or inappropriate for different types of riders, or different types of tires, or whatever.

http://www.precisiontandems.com/arttiresbymark.htm


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