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  1. #1
    Senior Member magohn's Avatar
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    Do you Max out your tire pressure?

    Hi all

    This weekend I had a second "tire explosion" while 15 miles from home. My Roubaixs original tires lasted 2000 miles and then the rear went out on me. In the last 6 months or so I have replaced the rear tire TWICE with similar Specialized Roubaix tires. Both have failed and at $60 a pop it aint funny anymore.However, could the problem be that I am over-inflating? The tires are rated to 8 BAR and I always pump approx 7.7 BAR into the tires before a ride. Now, I am in the 280lbs so I am wondering if the weight and the close to max pressure are the issue. Could it be that when I hit a pothole or similar that the tire pressure is increasing beyond the limit of 8 BAR and weakening the tire?

    It was a little humorous I guess. Early Sunday morning, and as I rode past the church in Carnation, WA, BBBBAAAANNNNNNNGGGG - It literally sounded like a gunshot going off. Birds flew out of the trees, church-goeers were startled and the Clyde in his lycra was sheepishly apologising and pointing at the tire. My wife was thrilled that she had to get out of bed and come get me on a Sunday morning

    Any thoughts on tire pressures for us bigger guys?

    P.S. Enough of the $60 tires. Just bought a pair of Nashbar Road 2 tires for $15 a piece. Good reviews too.

  2. #2
    SuperGimp TrojanHorse's Avatar
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    What kind of tires were you using?

    I have Michelin Pro3 tires that are rated to 115 psi and I inflate them to 115 psi every time I go for a ride. I did blow out a sidewall one time (tiny little pinhole, not really a blowout) but I think that may have been related to a little incident I had on some jagged cement a week earlier. Anyway, the Michelins are apparently slightly infamous for blowing out sidewalls.

    Hitting a sharp edged road hazard with any force is always a bad idea and can certainly result in the kind of issues you're facing.

    Other than that, no tire blowouts of any kind up to 240#.

  3. #3
    Senior Member magohn's Avatar
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    Specialized Roubaix Pro tires at 7.7 bar (approx 110 psi) - same brand with 2 blowouts.

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    Senior Member Seattle Forrest's Avatar
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    120 psi is fine.

    Why are you spending $60 per tire? They'd better be really fantastic to justify prices like that. You can get legendary GP4000s in the ballpark of $30 per tire, if you buy them online from stores in the UK. FYI.
    Don't believe everything you think.

  5. #5
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    I have been buying my tires as used specials at the bike coop and inflate them to around 70-80 percent of rated. I haven't had a blowout but i don't ride nearly as much as most people here. But still, 390 pounds on a used 27x1/4 inch tire is rather testing the limits. Same with my 700c tires.

  6. #6
    Carpe Velo Yo Spiff's Avatar
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    I'm running 700x25 Vittoria clinchers rated for 115psi. I usually inflate them to 105-110.

    I've sometimes had problems with rim/tire combos that just didn't get along and caused lots of pinch flats. Perhaps that's what is going on?
    2000 Bianchi Veloce, '88 Schwinn Prologue, '88 Trek 900, '92 Trek T100, 2000 Rans Tailwind

  7. #7
    Senior Member magohn's Avatar
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    Quote Originally Posted by Seattle Forrest View Post
    120 psi is fine.

    Why are you spending $60 per tire? They'd better be really fantastic to justify prices like that. You can get legendary GP4000s in the ballpark of $30 per tire, if you buy them online from stores in the UK. FYI.
    Weeelllll, The LBS was so understanding, supportive and positive when I wandered into their store 2 yrs ago at 320+lbs that I do like to support them whenever possible. They are a Spec. dealer and items such as tires are usually MSRP + tax. However, I think $120 on two tires that lasted (combined) less than 500 miles isnt going to fly anymore. I just ordered two Nashbar Road 2 tires for $40 shipped with almost 5/5 reviews.

    I do prefer to use the LBS but in this situation I feel forced to go online.

    People constantly aske me why I pull my brakes on descents and rarely go above 20 mph on a descent. This is the reason - 2 blowouts are unnerving. Not only the noise but the instant loss of control on the back end.

    Heres a pic:

    Last edited by magohn; 03-05-12 at 12:23 PM.

  8. #8
    Senior Member magohn's Avatar
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    Quote Originally Posted by Yo Spiff View Post
    I'm running 700x25 Vittoria clinchers rated for 115psi. I usually inflate them to 105-110.

    I've sometimes had problems with rim/tire combos that just didn't get along and caused lots of pinch flats. Perhaps that's what is going on?
    Thanks but this is more than a pinch flat. It sounds like a gunshot and literally blows out the side of the tire (not just the tube).

  9. #9
    Starting over CraigB's Avatar
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    I've routinely overinflated mine for 30 years without any problems, usually to about 115 or 120 psi. On a variety of (usually inexpensive) tires.
    Craig in Indy

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    Senior Member tardman91's Avatar
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    I wonder if it's a problem with your wheel? Is a spoke poking through the rim tape or something? I have Vittoria Pro tires that have a max of 145. I inflate the rear to 130 usually and the front to 120.

  11. #11
    Senior Member magohn's Avatar
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    Yikes - a search on the tire reveals lots of reviews of the Specialized Pro tire and its prone to "blow outs" (walls too thin) :

    http://www.roadbikereview.com/cat/wh...4_2489crx.aspx

    Many people with similar experiences with the tire. I will mount the "cheapos" when they arrive and inflate to the max and see what happens

    You live and learn I guess.

  12. #12
    Banned. Mr. Beanz's Avatar
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    Quote Originally Posted by magohn View Post
    Yikes - a search on the tire reveals lots of reviews of the Specialized Pro tire and its prone to "blow outs" (walls too thin) :

    http://www.roadbikereview.com/cat/wh...4_2489crx.aspx

    Many people with similar experiences with the tire. I will mount the "cheapos" when they arrive and inflate to the max and see what happens

    You live and learn I guess.
    With the exception of the classic Armadillo, I wil never use a Specialized "road" tire again. I used S-Works after a rec from a bud, rolls nice blah blah blah. After 500 miles, first ride up GMR, the thing was missing a 5 inch chunk of rubber. Later found out it was a common problem with the tire.

    I do run my tires at 120 psi. I do run an Armadillo on the rear of my bike. Rather deal with less flats. I recently place a "legendary" GP4000 on the front. Honestly , as I've always said, I see no difference in the ride. But guess what! I flatted, newish tire 400 mile (?). Who in the heck flats on the front tire onsmooth trail? I raerely flat in the front, this thing flatted in the front by way of small puncture. OK, a shotgun blast I can see but a small punctrure? Sheesh it's the front!

  13. #13
    Loves to suffer freighttraininguphill's Avatar
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    Yikes! The tread pattern on those looks exactly like the Specialized All Condition tires that came on my road bike and Sirrus. Both bikes still have those tires, and I have noticed cracking in the sidewall along the bead just above the rim, even when the tires were fairly new. I never inflate these much over 100 psi, even though they're rated for 115-125 psi. I keep a close eye on the sidewalls too. When they wear out I think I'll try a different brand.

  14. #14
    coprolite fietsbob's Avatar
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    Only pushed the PSI on my 622-40 Nokian A10 tires to 6 bar ,
    because the camping tour load
    and rolling resistance said to me it was more work, below that.

    47 wide tires, especially the 20" ones are fine .. just use the thumb
    rather than the gage.

    I just don't ride the Roadie bike much, as its not kitted out for rain.

  15. #15
    Senior Member socalrider's Avatar
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    yes you can overinflate by 10 psi easily.. Stop buying 60.00 tires that fail.. Been using Vittoria rubinos - wire bead models - spec'd to 145 psi, I usually inflate to 130psi with zero issues.. 46.00 for pair of tires.. I buy mine here

    http://www.ebay.com/sch/m.html?_nkw=...=bellsbikeshop

  16. #16
    Senior Member magohn's Avatar
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    Mr B - me too. As my Roubaix is all Specialized and the original tires were awesome, Ive been trying to chase that reliability. Perhaps they have changed their build process. All I know is once could be a fluke but twice is a pattern. Time to change.

    freight - Ive viewed your downhill descents . Your a braver person than me going at 30mph on a tire that could "blow". Mine was instant on both occasions. One second it was fine, the next a terrific bang (that really shakes you up) and the whole back-end wobble as the rim hits the road.

    I blame myself though - I should have "searched" on the tire before assuming brand and price equals quality!

  17. #17
    7-speed doomsday prepper ThermionicScott's Avatar
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    Could it be your mounting technique? It looks like the tube might have gotten pinched between the tire and rim, and dislodged the layer of tire fabric that contacts the rim when it blew.

    Try using a size smaller tube and inflating it a couple psi before stuffing it into the tire.
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  18. #18
    Am I evil? I am Man!!! Mr Sinister's Avatar
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    Quote Originally Posted by TrojanHorse View Post
    What kind of tires were you using?

    I have Michelin Pro3 tires that are rated to 115 psi and I inflate them to 115 psi every time I go for a ride. I did blow out a sidewall one time (tiny little pinhole, not really a blowout) but I think that may have been related to a little incident I had on some jagged cement a week earlier. Anyway, the Michelins are apparently slightly infamous for blowing out sidewalls.

    Hitting a sharp edged road hazard with any force is always a bad idea and can certainly result in the kind of issues you're facing.

    Other than that, no tire blowouts of any kind up to 240#.
    Just what I wanted to read... I bought a pair of these over the fall, and have changed my tires out to them.
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  19. #19
    fishologist cohophysh's Avatar
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    OP,
    I am a little heavier than you and am on 25's and I inflate them to about 100psi. I have Bontrangers and so far no problems.
    We cannot solve problems with the same level of consciousness that created them. A.E.

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  20. #20
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    The pressure inside the tire will not be affected more than a tiny, insignificant amount by even the heaviest rider sitting on the bike or when impacting a pothole or other bump. Tire pressure is inversely proportional to the total air volume inside the tube (PV=nRT). When you sit on the bike there'll be a very small decrease in the volume right at the contact patch area - but this is a tiny portion of the total air volume in the whole tire so the pressure increase is insignificant.

    Based on the picture, that looks like a defective tire unless the sidewall was cut in some way (such as by a brake pad mounted too high or a sharp object on the road that scratched the sidewall). Unless you're racing and at a level where the difference of a few seconds will be important then I see no reason to go with expensive tires. I haven't had any better experience wrt durability and reliability with $60+ tires as compared to ones that I buy for less than $10.

  21. #21
    Senior Member snowman40's Avatar
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    Vittoria. Recommended pressure >100 psi right there on the sidewall...

    I ride between 110 and 120, I inflate to 120.
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  22. #22
    Senior Member volosong's Avatar
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    Quote Originally Posted by cohophysh View Post
    ...am on 25's and I inflate them to about 100psi. I have Bontrangers and so far no problems.
    Same here. The 25's made all the difference in ride comfort. Max pressure on those tires are 100 psi. When I ran 23's, I also maxed out at 120 psi.
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  23. #23
    Senior Member tergal's Avatar
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    just a thought, are you sure your tyre pump pressure gauge is not screwy ? maybe it says 115 when really it is 125.

    do you have a separate one you can confirm with ?
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  24. #24
    Lover of Old Chrome Moly Myosmith's Avatar
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    I run my Bontrager H2 Ecos (700 x 28) at their rated 85 psi or even a couple pounds high when I'm riding exclusively on pavement. My Specialized All Conditions run at their rated 120 psi.
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  25. #25
    SuperGimp TrojanHorse's Avatar
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    Quote Originally Posted by Mr Sinister View Post
    Just what I wanted to read... I bought a pair of these over the fall, and have changed my tires out to them.
    Don't get my wrong, my pair have been great, comfy and grippy - no complaints! The issue I had was a direct result (I think) of a little riding stunt I did to get around my kids when they cut in front of me. I only buy them when they're on sale for $45 or less anyway.

    I was booking down a hill yesterday at about 45 mph and not worried at all about the tires. Since I just put the bike together about a week and a bit ago, I was PLENTY worried that maybe I didn't screw something on right.

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