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New Tyres Need to Grow before you stress them

Discussion in 'New Riders and Riding Tips' at netrider.net.au started by Mouth, Jul 30, 2005.

  1. New Tyres NEED to GROW before you stress them
    By James R. Davis

    Once again I heard well intentioned experienced riders only partially explain to some newbies that they needed to be careful after putting new tires on their bikes. They were told that this was because the new tires do not have as much traction on them until they are scuffed up a little.

    It is not that I dispute that fact - new tires do provide less traction until the new-tire coating is worn off of them. But that is not the whole story and if no more is said about them an inexperienced rider could do something very foolish and dangerous if they rely simply on that information.

    They could, for example, scuff the new tires using an abrasive just after mounting them and then take off to tackle some twisties. Lower traction would not, then, be a significant problem. But that is a far cry from saying that the new tires would be safely usable in stress situations as a result.

    ALL new tires grow during the first hundred miles or so of use. It is absolutely essential that you allow them to do so before putting them to a stress test such as attempting to aggressively navigate a set of twisties. Why? Because it is the process of growing that results in a tight and secure bead to rim seating. If you put the tires to undue stress before their beads have seated to the wheel rims there is a possibility that you will experience a catastrophic loss of air while heeled over in a turn.



    Rather than using an abrasive to convert a new tire into a used one, better by far to ride on them for a hundred miles or so. Besides, it's more fun doing it that way.

    [New or used, before you stress your tires in the twisties you MUST allow them to get warm first. Traction available on a cold tire is significantly less than for a warm one. Similarly, if you are doing a lot of twisties and your tires get HOT, traction is diminished. Maximum traction exists only under normal operating temperatures.]
     
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  2. Well, thank you for clearing that up for us!!!
     
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  3. Does this mean that I have to plant my new Bridgestones in the garden and let them grow for a bit???
    But actually, it's something I haven't thought about; iI would have thought with the sort of pressure the modern radial runs at the that the bead would be properly sealed from first fitting? (I understand the bit about temperature, of course)
    And having said all of that, we mediocre riders rarely if ever have to worry about such stuff anyway! :)
     
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  4. Although the whole idea makes a lot of sense, the bit about catastophic loss of air mid corner got me. Is this just a theoretical possibility, or has it been proven?

    Either way, I agree that a good scrubbing with the road is better than with sandpaper.
     
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  5. How does this explain how on some tracks the single best times is gained by "green" tyres rather than "roaded" or scrubbed tyres?
     
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  6. really brave riding!
     
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  7. ....but if you think about it, a bike leaves the pits on "green" tyres and has nearly a whole lap back to the start of the first timed lap. Depending on ambient heat, weight of the bike, abrasiveness or otherwise of the track surface, and many other factors, tyres should be ready to grip really well on the next (full) lap.
     
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  8. Question . Does just freeway riding (no twisties , just straight road ) heat the whole tyre or just the center ? Say it takes me 1 hour of freeay riding to get to any decent roads , would my tyres be warm enough to hit the twisties full on straight away or would i still have to take it easy until the sides have heated ?
     
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  9. Whole tyre
     
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  10. What a badly written article! :roll:
    The two points that i see this guy raising are that:-
    1. Tyres need to be scrubbed in to remove the 'new tyre coating' or what i had explained to me the other day as the wax that lines the tyre mould.
    2. That the process of fitting a tyre requires time to bed in, otherwise a catastrophic failiure may occur resulting in mid-corner loss of tyre pressure.

    Well, the first point has been discussed to death... a quick search will prove that.
    The second point i see as being rather an odd one. It's not as if a glue is applied to the inside of the rim where it contacts the tyre. I remember sitting watching my front tyre recently being fitted. Immediately after shoe-horning the tyre onto the rim a quick rapid inflation caused the tyre to seat itself properly on all edges of the rim; followed by a deflation, then correct re-inflation.

    As for the matter of the whole or part of the tyre being heated by commuting; even though in theory the 'core' of a tyre (McCoy terminology being adopted) may be heated through straight line riding, i always feel tentative about using the outer regions of rubber until i know that there is definitely some heat there (ie. it's scuffed up slightly). Although i've put this down to me being a chicken and not wanting to go hell-for-leather from the get go. ;)
     
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  11. If I was to guess, I'd say heating the tyre was more related to the temperature of the air inside the tyre as much as the rubber itself. Thus, the whole tyre is likely to be warm once you have run them for a few k's. That said, it's still a good idea to take it progressively further onto the sides of the rubber, particularly after commuting for a while: your tyres might not be clean. ;)
     
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  12. No, it is actually to do with the heat of the rubber rather than the heat of the air. Tyre compounds range from "cold" to "hot" (or hard to soft if you wish)

    Touring-type tyres have a harder compound, last longer, hang on less and take longer to warm up as the compound is harder.

    Sport-type tyres are the opposite.

    Both types should be warmed up until the compound is at its working temperature. That's why racers wiggle from side to side on the "warm-up" lap and that's why they use tyre warmers.

    The temeperature of the air in the tyres is of less importance than this. In some forms of motor sports where cars start out with fairly low pressure (drag racing, for example) part of the warm-up procedure consists of getting the temperature up so that the air inside the tyre expands and the tyre inflates to correct pressure. This happens in V8 Supercars and also NASCAR.

    But no road rider is going to be putting the g-forces into their tyres that are common in this type of competition and, even if they did, the difference in pressure between a hot tyre and a cold tyre is going to make only a negligible difference in how the bike handles.
     
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  13. I found the other day that while the tyres were at operating temp, I was negotiating corners at my usual stid speed. I stopped for a while and they cooled. The next few Ks it certainly felt as if they were slipping a little. After they warmed up it was back to normal.

    Now that may be all put down to my just getting back into the grove so to speak. Which?

    On the subject of blowout, when a tyre is fitted they use (some places) a soap type glue to allow the tyre to seat properly on the bead.

    I cannot see how you could possibly pull a tyre off properly fitted. Sorry I can't. 35lb per sq in. The tyre would really have to squirm.

    At any rate, if I was worried about it, I would simply fit a tube. Porblem over. If the tyre did leave a minute gap, the tube would still retain the pressure etc.


    I just had my tyre punctured by a nail (clout tack actually) it went down slow enough to allow me to stop quite safely.
    When it was repaired we found it had a tube in it. I had no idea. So now it has a new tube, scrubbed tyre, so away I go.
    <Edit - typo>

    Brian
     
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