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Is it safe to run directional tires backward

  1. #1
    Member martia's Avatar
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    Is it safe to run directional tires backward


    Hi I wanted to see if it is safe to run directional tires backward as my left side is worn down but right side is good. I will be running Thompson CCT which has 7 lefts and 3 rights. I am on a budget and just need to get everything out of my tires. Tire is a Pirelli Diablo Supercorsa V2

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  2. #2
    KNEE DRAGGING BAGGER sedanman's Avatar
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    Re: Is it safe to run directional tires backward

    Short answer, no. Someone must have a take-off that is in better condition than your tire. But seriously, tires are the only thing between your bike and the pavement, skimp elsewhere. Ramen is cheap and almost food.

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  3. #3
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    Re: Is it safe to run directional tires backward

    I've run tires backwards on the track w/ no problems. I was told the siping (grooves) are there for water dissipation. The sipes don't work well if running the tire backwards, but if you're in the dry then no biggie.

    Shot is shot though. If 1 side is truly totally worn out, I'd get a new tire.

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  4. #4
    Super Moderator OreoGaborio's Avatar
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    Re: Is it safe to run directional tires backward

    If it's SAFE on both sides, but worn unevenly, go ahead & flip it.

    But if it's TOAST on one side then it's toast on one side no matter how it's mounted and shouldn't be ridden on.

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    Bizarro Zoolander Petorius's Avatar
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    Re: Is it safe to run directional tires backward

    So why are we all not doing this?

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  6. #6
    Super Moderator OreoGaborio's Avatar
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    Re: Is it safe to run directional tires backward

    Because you might... MIGHT get one more day out of a tire and it's not worth the effort to most people.

    Race tires are a consumable item. They're not designed to last a million miles, they're designed to GRIP. And when that grip starts to taper off (usually before it gets noticeably worn on one side more than the other), you get rid of it.

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    Last edited by OreoGaborio; 09-16-15 at 05:01 PM.
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  7. #7
    Lifer Rosco61's Avatar
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    Re: Is it safe to run directional tires backward

    I have some used Q3's in my garage you can grab for cheap cheap money. 120/17 and 190/55 17's

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  8. #8
    Is this thing on? Mr. Kurtz's Avatar
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    Re: Is it safe to run directional tires backward

    Quote Originally Posted by OreoGaborio View Post
    Because you might... MIGHT get one more day out of a tire and it's not worth the effort to most people.

    Race tires are a consumable item. They're not designed to last a million miles, they're designed to GRIP. And when that grip starts to taper off (usually before it gets noticeably worn on one side more than the other), you get rid of it.
    I'm putting this on a t shirt.

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  9. #9
    WMC original sdog30's Avatar
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    Re: Is it safe to run directional tires backward

    Tire flips are a daily thing in jersey. I was told that the worn side of the tire heats up quicker when riding since the rubber is thinner there.

    And Kian is totally right about the sipping only being there for water dispersion. In race tires, it's just there to make them ss legal. Even the new Dunlops gp pro's are unidirectional in tread and made to be flipped.

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  10. #10
    Posting Freak xsiliconkid's Avatar
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    Re: Is it safe to run directional tires backward

    1. What heats a tire up (other than warmers) is the flexing of the side walls/ carcass) not related to thickness of tread area
    2. The tire's tread/ slick area is a strip that is wrapped around the circumference of the tire and overlapped where they meet, then vulcanized. Mounting backwatds will have the tendency to peel back this layer.

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    Re: Is it safe to run directional tires backward

    Quote Originally Posted by xsiliconkid View Post
    1. What heats a tire up (other than warmers) is the flexing of the side walls/ carcass) not related to thickness of tread area.
    .....and.....FRICTION! dramatically more so than flexing. The amount of rubber on the carcass is directly related to the amount of heat it will absorb/retain. So thinner gets hotter quicker. Savvy?

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  12. #12
    Posting Freak xsiliconkid's Avatar
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    Re: Is it safe to run directional tires backward

    I have to differ with you here. Friction has little to do with tire carcass temp.
    Hard braking and acceleration (flexing the carcass) creates heat in a tire.
    weaving side to side does nothing

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  13. #13
    Backwoods lobster boy number9's Avatar
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    Re: Is it safe to run directional tires backward

    Quote Originally Posted by xsiliconkid View Post
    I have to differ with you here. Friction has little to do with tire carcass temp.
    Hard braking and acceleration (flexing the carcass) creates heat in a tire.
    weaving side to side does nothing
    Is this only true for motorcycle tires? For instance, with automobile drag racing, you commonly see burn-outs which are said to raise the temperature of the tire dramatically. And that's friction, no?

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    Re: Is it safe to run directional tires backward

    Quote Originally Posted by number9 View Post
    Is this only true for motorcycle tires? For instance, with automobile drag racing, you commonly see burn-outs which are said to raise the temperature of the tire dramatically. And that's friction, no?
    A burn out is slightly different from weaving side to side or normal, not break the tire loose hard accel / braking.

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    Re: Is it safe to run directional tires backward

    Quote Originally Posted by number9 View Post
    Is this only true for motorcycle tires? For instance, with automobile drag racing, you commonly see burn-outs which are said to raise the temperature of the tire dramatically. And that's friction, no?
    It is, but burn-out friction is surely different from regular contact. Technically, both surface friction and flex create heat. I thought the general rule of thumb is that the flex is what creates meaningful heat.

    I realize this is about car tires, but probably still interesting - Hoosier drag tires: "The goal of the burn out is to clean all debris off the tires and heat the just the surface of the tread." They also say "Hoosier does suggest, depending on the number of runs, swapping tires on a regular basis. The main reason for swapping tires is to help smooth out or even the tread wear. By swapping tires, it causes the tire to be run backwards, thus causing the tire to wear differently, which cleans up the tire tread" https://www.hoosiertire.com/faqdrag.htm

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    Lifer loudbeard's Avatar
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    Re: Is it safe to run directional tires backward

    The flexing of the tire increases the contact patch. The increased contact patch causes more friction, that's where the heat comes from.

    Run a test:
    Take a rubber band, rapidly extend and contract it repeatedly for x number of seconds. Is it hot?
    Take the same rubber band, rub it back and fourth across an abrasive surface for the same amount of time. Is it more hot than the first test? You'll find the answer to be yes.

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  17. #17
    Lifer Kurlon's Avatar
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    Re: Is it safe to run directional tires backward

    Quote Originally Posted by Pinned View Post
    The flexing of the tire increases the contact patch. The increased contact patch causes more friction, that's where the heat comes from.

    Run a test:
    Take a rubber band, rapidly extend and contract it repeatedly for x number of seconds. Is it hot?
    Take the same rubber band, rub it back and fourth across an abrasive surface for the same amount of time. Is it more hot than the first test? You'll find the answer to be yes.
    Now, to simulate what's actually going on, take that rubber band and stretch it around a plastic bottle. Now take that bottle and roll it around on the band. Note the lack of heat.

    More to the point, increasing the size of the contact patch does not increase the friction. The friction coefficient doesn't change based on the size of the patch. Unless the tire is sliding, there is no friction induced heat. You're back to just the heat of material deformation in which case a larger patch deforms the rubber less as the work area is larger. Upping the pressure so your patch is smaller will increase the point loading and make for a hotter localized zone which can be seen as tearing when you go too far.

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  18. #18
    Lifer Jim's Avatar
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    Re: Is it safe to run directional tires backward

    Quote Originally Posted by martia View Post
    Hi I wanted to see if it is safe to run directional tires backward as my left side is worn down but right side is good.

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    Back marker... jwm2k3's Avatar
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    Re: Is it safe to run directional tires backward

    My head hurts...

    I've got a set of Q3's I ran 5 races with that I took off. They are free if you come get them....

    120/180

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  20. #20
    ^ It's my bike and my car tls25rs's Avatar
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    Re: Is it safe to run directional tires backward

    A few years back there was a racer named Gary McCoy that used to spin up his tire coming out of just about every turn and people theorized that he would destroy his tire riding that way. Well he didn't destroy his tires and some research was done that while he was spinning the tire up all the time it was only heating the surface of the tire up and not the carcass which made it such that it did not hurt the performance or life span of the tire in any great fashion. This would make me think that friction is not the driving force in heating of a tire and more the flexing and bending of the carcass during hard acceleration and deceleration.

    Just my $0.02

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  21. #21
    Posting Freak xsiliconkid's Avatar
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    Re: Is it safe to run directional tires backward

    Quote Originally Posted by tls25rs View Post
    A few years back there was a racer named Gary McCoy that used to spin up his tire coming out of just about every turn and people theorized that he would destroy his tire riding that way. Well he didn't destroy his tires and some research was done that while he was spinning the tire up all the time it was only heating the surface of the tire up and not the carcass which made it such that it did not hurt the performance or life span of the tire in any great fashion. This would make me think that friction is not the driving force in heating of a tire and more the flexing and bending of the carcass during hard acceleration and deceleration.

    Just my $0.02
    To complete that story, Gary would spin up the rear exiting the first turn of the esses then chop the throttle so it literally high sided the bike (flicked) into the entrance of second turn of the esses.

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  22. #22
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    Re: Is it safe to run directional tires backward

    Quote Originally Posted by xsiliconkid View Post
    To complete that story, Gary would spin up the rear exiting the first turn of the esses then chop the throttle so it literally high sided the bike (flicked) into the entrance of second turn of the esses.
    Gazza could do many, many things that us mere mortals could never even imagine, let alone hope to do.

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  23. #23
    go faster cdovego's Avatar
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    Re: Is it safe to run directional tires backward

    Quote Originally Posted by xsiliconkid View Post
    To complete that story, Gary would spin up the rear exiting the first turn of the esses then chop the throttle so it literally high sided the bike (flicked) into the entrance of second turn of the esses.
    1. He was a ballsy dude.
    2. He broke a lot of bones.

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  24. #24
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    Re: Is it safe to run directional tires backward

    Quote Originally Posted by cdovego View Post
    1. He was a ballsy dude.
    2. He broke a lot of bones.
    oddly enough, the two go hand in hand

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  25. #25
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    Re: Is it safe to run directional tires backward

    Quote Originally Posted by tls25rs View Post
    A few years back there was a racer named Gary McCoy that used to spin up his tire coming out of just about every turn...
    I bet if the tire was mounted backwards, it would cool down instead of heat up.

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