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  1. #1
    Senior Member brianinc-ville's Avatar
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    Max. Tire Pressure with Straight-Sided Rims?

    Question: when you use modern tires with C&V straight-sided clincher rims, do you inflate to the maximum rated pressure? If not, how much do you back off? Has anyone actually had a blowout due to overinflation in this situation?

  2. #2
    Senior Member fender1's Avatar
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    85 psi and I never had any issues. YMMV.

  3. #3
    Senior Member Roger M's Avatar
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    I did over inflate mine to 85 pounds..once. Blew out when I stood up on the pedals to climb a hill. I run mine at about 65. You will probably get other opinions from people that have been running 27s longer than I.

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  4. #4
    perpetually frazzled mickey85's Avatar
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    Depends on the rim, the tire, and your weight. Using Bell Streetster 27X1-1/4's, I find that my fat self can go to about 75psi safely, but I usually run 70.
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  5. #5
    Champion of the Low End Primitive Don's Avatar
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    Customer brought in a Sports Tourer, saying he'd blown the tire off of the original rim when he inflated to 90PSI as per the tire rating.
    87 Trek 560EX * 83 Schwinn Traveler * Sanwa SS Conversion * 80s Chicago Schwinn Traveler SS/FG Conversion * 2011 Fuji Sagres 2.0

  6. #6
    Senior Member Roger M's Avatar
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    The tire rating is given in the thinking that the tires will go on rims that are hooked.

  7. #7
    Gearhead old's'cool's Avatar
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    Some tires give different ratings for hooked and non-hooked rims. If there's only one rating, it's probably for hooked. For non-hooked, a safe bet would be 20% or 20 psi lower.
    Geoff
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  8. #8
    Senior Member brianinc-ville's Avatar
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    Excellent, thanks everybody.

    Further question: what reasonably affordable 27 x 1 1/4 tire would you put on a '51 Raleigh Clubman?

    Looking for something both fast (considering the pressure limitation) and accurate-looking; durability is less of a concern, since it won't be a daily rider and won't be taken on long tours.

  9. #9
    Я люблю суп abarth's Avatar
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    Really depends on the model and the size of tire. I have no problem running 95psi on Performance Bike brand 27 x 1-1/4.

  10. #10
    Senior Member southpawboston's Avatar
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    Quote Originally Posted by mickey85 View Post
    Depends on the rim, the tire, and your weight.
    agreed. it really depends on all three above factors. i have a set of continental sport 700x25C on concave weinmanns (non-hooked) and i never go above 75. i haven't had a blowout, but i don't want to risk going higher.

    on another bike with heavy stainless steel non-hooked rims and schwalbe 200x35C tires, anything over 70lb was a guaranteed blowout.

  11. #11
    Broom Wagon Fodder reverborama's Avatar
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    I regularly use 85lbs with wire-bead 27 inch tires on non-hooked rims and have never had a blowout. I never run folding tires on non-hooked rims.

  12. #12
    PanGalacticGargleBlaster Zaphod Beeblebrox's Avatar
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    I don't go above 70psi with non-hooked rims. I had both the front and rear tire blow off within 2 minutes of each other last weekend. Panaracer Paselas on non-hooked 27" Peugeot UO-8 rims...pumped to 85 psi, started filling the tires on another bike and i hear "Rrrrrrrrrrrrrrrrrrrrrrr BANG!!" there goes the front. 2 seconds later the same creaking noise is coming from the back wheel and I got wise and took cover...."Rrrrrrrrrrrrrrrrrrr BANG!"

    thats the sound of blowing your cash on 2 new tubes
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  13. #13
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    Quote Originally Posted by reverborama View Post
    I regularly use 85lbs with wire-bead 27 inch tires on non-hooked rims and have never had a blowout. I never run folding tires on non-hooked rims.
    +1 to that. I run wire-bead 27 x 1 1/4" tires on non-hooked rims at around 80 psi, which is also what I run folding 27 1 x 1/4" tires on hooked-bead rims.

    On my two 27" wheel Clubman, I have Continental Sport tires on one and Bontrager skinwall tires on the other.

    Neal

  14. #14
    aka Phil Jungels Wanderer's Avatar
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    Back in the day ---- we would pump 'em up to whatever the tire (27X1, 27X1 1/4) was rated for ---- 85, 90, 95, 100 PSI. Never had a problem.

    "Retirement is the best job I ever had!" Me, 2009


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    Senior Member Chombi's Avatar
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    I have a related question, how is a hooked and unhooked rim physically different. I always wondered what my 80's rims are. There seems to be just s small bump/ridge at the insde edges of the rim to possibly hook the bead, but should I be looking for an actual "hook" shape that the bead would insert into? Are unhooked rim edges totally flat on the inside...please advice.
    I have Hutchinson Atom tires on on my clincher wheelset right now that I pump up to 110 - 115PSI.....it hasn't blown off yet, but I'm not wanting to find out on the road for myself one day.....

    Chombi

  16. #16
    Senior Member southpawboston's Avatar
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    Quote Originally Posted by Chombi View Post
    I have a related question, how is a hooked and unhooked rim physically different. I always wondered what my 80's rims are. There seems to be just s small bump/ridge at the insde edges of the rim to possibly hook the bead, but should I be looking for an actual "hook" shape that the bead would insert into? Are unhooked rim edges totally flat on the inside...please advice.
    that small bump/ridge is the hook. that bump is what keeps the bead from lifting up and over the rim wall.

  17. #17
    Senior Member bibliobob's Avatar
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    I've been running 90 psi on the front (Weinmann unhooked) with Pasela non TG. 105 psi in the back, but that's been changed to a hooked Araya. I'm a big guy (205 lbs.) and don't want to run less than 85 psi.

    No problems so far, knock on wood.
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  18. #18
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    too many small differences between tires and rims to say anything for certain. just like how sometimes when replacing, the tire comes off real easy and other times it takes twenty minutes of knock down drag out fighting to pry it off.
    1988 Miele Azsora

  19. #19
    DRF aka Thrifty Bill wrk101's Avatar
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    Quote Originally Posted by Wanderer View Post
    Back in the day ---- we would pump 'em up to whatever the tire (27X1, 27X1 1/4) was rated for ---- 85, 90, 95, 100 PSI. Never had a problem.
    +1 Back in the day, 1975/1976 era, I used to run Michelin Elans on my 1975 UO8, which I had upgraded with Araya unhooked rims. Routinely ran between 100psi and 110psi. Then about two years ago, I had a blow out on the exact same bike. The reason: poor installation on my part, bead was not fully seated evenly. Wire beaded Performance (Forte) tires. But it was not the tires, it was my installation...

  20. #20
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    Quote Originally Posted by Chombi View Post
    I have a related question, how is a hooked and unhooked rim physically different. I always wondered what my 80's rims are. There seems to be just s small bump/ridge at the insde edges of the rim to possibly hook the bead, but should I be looking for an actual "hook" shape that the bead would insert into? Are unhooked rim edges totally flat on the inside...please advice.
    I have Hutchinson Atom tires on on my clincher wheelset right now that I pump up to 110 - 115PSI.....it hasn't blown off yet, but I'm not wanting to find out on the road for myself one day.....

    Chombi
    Frank Berto called that "bulged". I have that on my Rigida AL1622s. It's NOT the same as the "hook" on my more recent vintage rims. I've gone around 105 without any trouble but I'm still leary about using a folding, kevlar bead tire.
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  21. #21
    Bottecchia fan
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    Just as a point of reference, my 1974 Bottecchia had Fiamme yellow label wide clincher rims shod with Clement 27 x 1 1/4 tires rated at 100-psi. I never blew those off. The Performace 27 x 1" tires out in the garage right now actually say on the sidewall "Recommended Pressure 110 P.S.I Max 125 P.S.I with hooked bead rim".
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  22. #22
    Bike Junkie roccobike's Avatar
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    I go 80PSI max on a straight side rim.
    I go up to 105 PSI on buldge bead rims.
    I'll go what ever the tire says on a true hooked bead rims. I have two sets of true hooked bead 27" rims. All the rest are buldge with a few straight side.
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  23. #23
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    I run 75/85 front/rear on 27x1 1/4. Max pressure listed on the side of the original (factory) tire read 75psi. The new ones listed 110 as the max. I bought one from an LBS and installed it in the parking lot because I'm a cheapskate and didn't want to pay the labor. When I brought the wheel back in and asked the guy to air it up, he asked what pressure I wanted. Me, weighing 250lbs, said "what ever the max is listed on the side".
    I then received a verbal beat down and explanation as to why I don't want to do that.

    Also, in another thread someone provided a link to a document that listed optimal tire pressures for weight. This is known as "Tire Drop". The graph shows my running pressures as optimal, and I agree. I am happy with how the tires behave at these pressures.
    The pressures are listed for each wheel.
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    I checked out my '77 Schwinn Traveller using the bathroom scale method and the city bike ratio was dead on.
    Last edited by Scrockern8r; 09-09-10 at 09:46 PM. Reason: added ratios
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  24. #24
    Gearhead old's'cool's Avatar
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    Quote Originally Posted by wrk101 View Post
    ... Then about two years ago, I had a blow out on the exact same bike. The reason: poor installation on my part, bead was not fully seated evenly. Wire beaded Performance (Forte) tires. But it was not the tires, it was my installation...
    You say that, but the only times I've ever had a tube blow out between the wire bead and the rim have been with Forté tires, and now that you mention it, in combination with Forté tubes. And that is with inflation pressure at or below the rating for straight sided (i.e. non-hooked) rims.
    I'm not sure yet whether it is a deliberate conspiracy to make up for the low sales price by selling losts of replacement tubes due to the blowouts, or just because they are cheap crap. I actually think the Forté kevlar tires aren't so bad for the price, but I won't be be buying any more of their entry-level tubes.
    Geoff
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  25. #25
    Senior Member southpawboston's Avatar
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    Quote Originally Posted by wrk101 View Post
    +1 Back in the day, 1975/1976 era, I used to run Michelin Elans on my 1975 UO8, which I had upgraded with Araya unhooked rims. Routinely ran between 100psi and 110psi. Then about two years ago, I had a blow out on the exact same bike. The reason: poor installation on my part, bead was not fully seated evenly. Wire beaded Performance (Forte) tires. But it was not the tires, it was my installation...
    interesting... i had forte kevlar bead tires on non-hooked rims and they routinely blew at >80psi. the tires were rated at 95psi. then with the same rims, schwalbe marathon wire bead tires blew off at >80psi. therefore i blamed the rims, not the tire, the bead or the installation.

    Quote Originally Posted by old's'cool View Post
    You say that, but the only times I've ever had a tube blow out between the wire bead and the rim have been with Forté tires, and now that you mention it, in combination with Forté tubes. And that is with inflation pressure at or below the rating for straight sided (i.e. non-hooked) rims.
    I'm not sure yet whether it is a deliberate conspiracy to make up for the low sales price by selling losts of replacement tubes due to the blowouts, or just because they are cheap crap. I actually think the Forté kevlar tires aren't so bad for the price, but I won't be be buying any more of their entry-level tubes.
    i wonder if it is not so much the brand of tire, but the design. were older tires from the non-hooked rim days designed with a different bead? was the rubber around the bead molded differently so as to seat differently than today's modern tires, which are designed around hooked rims? just a thought...

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