Thunderbird 900 Sport ‘04 Tires!

Discussion in 'Tyres' started by Cabron, Feb 11, 2020.

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  1. Cabron

    Cabron New Member

    Feb 11, 2020
    5
    3
    Sweden
    Hi!
    I’m a proud and happy owner of thunderbird 900 sport from 2004 and I need to change tires. Now I fall in love with Bridgestone ax41s but the only problem is that their rear tire in my rim size is 160/60r17 instead of 160/70r17 like i suppose to have. Front one is exactly the same size. So now my question is, if I would put rear tire with lower aspect ratio how much would it affect handling? Is it worth it or it doesn’t make sense? Help me out here fellas!
     
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  2. Callumity

    Callumity Elite Member

    Feb 25, 2017
    3,358
    800
    Nr Biggar
    I would fit a Michelin Anakee III in the OEM size. The manufacturers test size and profiles pretty exhaustively. I assume you intend to stray onto loose surfaces.
     
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  3. Cabron

    Cabron New Member

    Feb 11, 2020
    5
    3
    Sweden
    Thanks for your input! I’m planning to stay mostly on hard roads but I would also like to go a little bit off main track to go camping somewhere by the lake or so (living in Sweden so there’s a lot of nice places for a weekend trip) The idea with Bridgestone ax41s is that they are a little bit more aggressive/scrambley looking and that’s what I’m aiming for, don’t want to ruin joy of ride tho!
     
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  4. dirty big hands

    dirty big hands Active Member

    Aug 4, 2017
    183
    43
    sussex
    I'm also a proud owner of a TBS.
    However, I'm only a few years into biking and have no experience of a different tyre profile than the manufacturers recommended size.
    I have Avon storm 3D XM on mine, again I'm not experiencing enough to compare them with much else.
    Hope that helps :laughing:
     
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  5. Cabron

    Cabron New Member

    Feb 11, 2020
    5
    3
    Sweden
    Every opinion gives me better view on the matter;)
     
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  6. Wire-Wheels

    Wire-Wheels Elite Member

    Apr 26, 2019
    2,481
    800
    California - USA
    #6 Wire-Wheels, Feb 14, 2020
    Last edited: Feb 14, 2020
    When it comes to handling what you would be concerned with would be radius not overall diameter. As I figure it, an aspect ratio difference of 10% [from 70 to a 60] would only mean a decrease in radius of 16mm. I am running a 160/60X17 on my Legend [a very similar chassis] and it handles fine. If you really needed to, you could slide your front fork up 16mm to make up the difference. I don't think you would notice it that much in handling. You might notice a bit of change in engine RPM. It won't be much, but you engine will spin a bit faster per a given speed than it did before. One positive in this would be you would lower your C.G. in the process. You pay your money, and take your choice....J.D.
     
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  7. capt

    capt Elite Member

    May 8, 2016
    3,052
    750
    western Australia
    #7 capt, Feb 14, 2020
    Last edited: Feb 14, 2020
    Going thinner on the back wheel by that tiny amount as @Wire-Wheels calculated , would sharpen, speed up the bikes turning in , that would be my thoughts !
    I put one size wider on both front and rear on my Laverda many years ago , the wider front caused two things to happen. Slower turn in response and slight under steer ! But that was possibly lessened by a wider rear !
     
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  8. Wire-Wheels

    Wire-Wheels Elite Member

    Apr 26, 2019
    2,481
    800
    California - USA
    The tire is not thinner. Both are 160 section width. A 160/70X17 has a side wall that is 70% of the section width. A 160/60X17 is not thinner. It is however shorter. It's sidewall is only 60% of the 160mm section width. ...J.D.
     
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  9. joe mc donald

    Dec 26, 2014
    13,874
    1,000
    slough / burnham
    Carbon
    Welcome to the family.
    Do hit the upload a file button bottom right corner and show the inmates your beast.
    Regards & Ride Safe
    Joe
     
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  10. Cabron

    Cabron New Member

    Feb 11, 2020
    5
    3
    Sweden
    Thanks for your answer! Wouldn’t sliding front fork up by 16mm double the difference instead of countering it? If I’m going to put slightly “lower” tire only on the back wheel that means the entire back is going 16mm lower, wouldn’t that make go front a little up? Or maybe not up but change the angle?
     
  11. Wire-Wheels

    Wire-Wheels Elite Member

    Apr 26, 2019
    2,481
    800
    California - USA
    When I say to move the fork up, I mean slide it up in it's mountings. By so doing, you are brings the bike down. This is measured by the distance the fork tube sticks out of the top clamp. You need to increase that value. If I were doing the setup myself I would measure the old tire/wheel assembly and the new one to make sure of the amount of change needed. Don't just use my estimated numbers. If you are really serious about handling, you may also need to fine tune this adjustment. When you get in this deep, you are re-engineering things. You have to be the engineer yourself at that point. ..J.D.
     
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  12. Cabron

    Cabron New Member

    Feb 11, 2020
    5
    3
    Sweden
    Good to know, I’m probably going to put 160/60 after all, without trying to reinvent the motorbike on the way :p I’m going to do it in about a month or so, will write if I can feel any noticeable difference.
     
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  13. Wire-Wheels

    Wire-Wheels Elite Member

    Apr 26, 2019
    2,481
    800
    California - USA
    I would like to read what happens. It is one thing to have a conversation and quite another when you get in and do it. You always run in to those "unintended consequences" that keep the workshop lights on late. ...J.D.
     
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  14. johan hedblom

    johan hedblom New Member

    Jul 22, 2020
    7
    3
    Sweden
    @Carbon.
    What tiers did you finally decide on and how is your experience so far riding the bike this summer?
     
  15. Cabron

    Cabron New Member

    Feb 11, 2020
    5
    3
    Sweden
    After changing my mind 2000 times I decided to go with Bridgestone ax. So far I made between 3-4K km and I can’t really complain. They have good grip on wet and dry and they looks extremely good. I can definitely recommend although it took few kilometers to get use to them. They feel different but not in a “wrong” way. I’m going to post some pics if I’m gonna make it but overall it was a good decision and I’m glad I went for them.
     
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  16. Cabron

    Cabron New Member

    Feb 11, 2020
    5
    3
    Sweden
    First pic I had on my phone, will try to post something better later

    2053CE7E-35B8-4FC6-9BCF-E14300FB1F4F.jpeg
     
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