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Radial Tire Thread

Discussion in 'V7/V85/V9 Chat & Tech' started by Bncprf, Mar 26, 2017.

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  1. MotoBug

    MotoBug Tuned and Synch'ed

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    I reckon the front sport demon will last another rear sport demon.
     
  2. Stradagene

    Stradagene Cruisin' Guzzisti

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  3. Faisal

    Faisal Tuned and Synch'ed

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    Took a quick glance on the forum and this thread, I may have missed it or this question might have not been asked, but nevertheless, I cannot find the answer to my question, which is: What is the max tire size the stock rims on the V7II Racer will accept?

    I'm looking to purchase some Avon Roadriders for my V7II, and I wanted to install some beefier tires for aesthetic reasons, and I doubt they'll affect riding much. I'm looking to purchase the 140/90-17 and the 110/90-18, will those fit my bike without complications? 140/80-17s are available if the 140/90-17s don't fit. I would like to fit some 120/80-18s in the front but I feel 20 millimeters over stock tires won't fit properly, I just need some enlightening before I make any purchases, please.

    Edit:

    Just to make this easier to understand, which tire will fit properly:

    Rear: 140/80-17 , 140/90-17
    Front: 110/80-18, 110/90-18, 120/80-18

    Thank you
     
  4. Godfrey

    Godfrey High Miler GT Famiglia

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    Faisal: One of the biggest mistakes I ever made in buying tires for a motorcycle was putting larger than spec tires on it, particularly on the front. Handling suffered badly, and the propensity to get into tank slapping wobbles became a serious concern. I took them off and put standard sized tires on, and all the excellent handling and stability returned immediately.

    The difference in size was 10mm in the front.

    When I went to build a modified, improved bike of the same model, and year, I changed the rims first (front: went from 19" to 18", went from 1.75" to 2.5") and then went to a wider, lower profile tire that provided the same overall diameter as the originals. And I did the same kind of changes to the rear rim and tire sizing, actually going to a slightly taller tire to quicken the steering geometry a tiny bit. That worked beautifully.

    So I would think carefully about these changes "for aesthetic reasons" ... Motorcycle steering geometry and handling characteristics are subtle things, and generally the manufacturers have a very good handle on how to make motorcycles work well these days. Look carefully at other models similar to the VII Racer, see what rim/tire/stock geometry settings are, and make changes that replicate those. Just looking for "the biggest that will fit" is rarely the best in these situations.
     
    Last edited: Feb 23, 2018
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  5. Faisal

    Faisal Tuned and Synch'ed

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    Well, would you look at that.. Size does matter... Were the 10mm and standard sized tires the same brand and type?
     
  6. Godfrey

    Godfrey High Miler GT Famiglia

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    It was a very long time ago (1979-1980, if I recall correctly) ...

    I believe the reason I went to the larger size was, well, because they were bigger and looked cool to my eye, and they were a different brand/model from the original tire because the original tires were not easily available (and completely worn out: I desperately needed a set of tires at that moment!). The smaller OEM sizes that worked perfectly were the same alternative brand/model.


    "We all get to be young and foolish in our lives. If we survive that, we get to be old and foolish."
     
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  7. GT-Rx®

    GT-Rx® Administrator Staff Member

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    Unfortunately that is the time/trend we are in right now. Glorified, actually. Knobby tires and brown seats are getting all of the money.
    So interestingly enough for 2017, Guzzi actually lists the 110/80-18 & 140/70-17 as options on the V7. I have run these (Metzeler Klassik) sizes on many bikes, and they are OK. A 140/70 makes you pull the rear drive to get fitted.
    I actually prefer the 110/80 Conti RAIII as it is Z rated, and transforms the bike. They only make a 130/80 rear offering.
     
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  8. Faisal

    Faisal Tuned and Synch'ed

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    I don't mean to be rude with this upcoming question, I may just be young and inexperienced, but don't you think after 38 years since your anecdote that tire technology has greatly improved? Don't you think if you had done that modification nowadays that it wouldn't have as much of an affect as it did in 1980?

    A little bling never hurt anyone ;) Since Guzzi mention those sizes as options, I'm guessing handling won't be compromised. Thank you, Todd.
     
  9. Godfrey

    Godfrey High Miler GT Famiglia

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    I don't see the Conti RA3 available in 110/80R18 front size, only the 100/90R18 size. ?
     
  10. Godfrey

    Godfrey High Miler GT Famiglia

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    Steering geometry that works hasn't changed in 100 years. Chassis and suspension have improved enormously, tire technology and brakes are light years ahead, but handling dynamics don't change because they are dependent on the physics of two-wheeled vehicle dynamics.

    The V7III chassis is just an slightly improved version of a 1972-generation motorcycle chassis, with forks and good rear suspension, so 1970s technology is actually well worth considering when looking at how to modify its performance and handling.
     
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  11. GT-Rx®

    GT-Rx® Administrator Staff Member

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    I can get them:

    ContiRAIII-Snip.JPG
     
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  12. Godfrey

    Godfrey High Miler GT Famiglia

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  13. vagrant

    vagrant Cruisin' Guzzisti GT Contributor

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    so somebody who actually has put some miles on, how are the radials doing for wear on the V7 as compared to the stockers.
     
  14. Stradagene

    Stradagene Cruisin' Guzzisti

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    I don't have the numbers on hand, but the RAIIIs that I put on my V7R are wearing much better than the Sport Demons. I expect to get at least twice as much wear out of them if not more.

    It makes sense. Despite most of my riding being twisties the Sport Demons nevertheless seemed to wear flat along centerline in my hands. The RAIIIs have a harder compound down the centerline which has so far shown itself to resist the tendency to wear flat so quickly.
     
  15. spowell

    spowell Just got it firing! GT Contributor

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    Todd, is your preference for the larger 110/80 and the stock 130/80 RAIII combo have to do with feel, steering quickness or something else entirely?
     
  16. GT-Rx®

    GT-Rx® Administrator Staff Member

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    Both of those, and the Conti RA III stock front size (100/90) is a little on the narrow side, though does not affect the bike, handling or traction of course. Both are good. As an ex-Pro Racer, I like what the 110/80 does to the bike, and I like the looks on the rim better (more modern look for those who care).
     
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  17. spowell

    spowell Just got it firing! GT Contributor

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    Good info. Thanks. I thought the Conti's radials in the stock size would be narrower since the service width of the RAII's is a little smaller. So, I'll probably try the 110/80's next.

    From my research, for those that are comparing:

    Size/Model |Measured/Tested Rim Size|Rim Range|Service/Inflated Width(mm)|weight(lbs)

    100/90 - 18 M/C 56H TL SPORT DEMON | 2.50 | 2.15-2.75 | 114 | 11.9
    110/80 - 18 M/C 58V TL SPORT DEMON | 2.50 |2.15-3.00 | 125 | 12
    130/80 - 17 M/C 65H TL SPORT DEMON | 3.00 | 2.50-3.50 | 147 | 14

    100/90 R 18 M/C 56V TL ContiRoadAttack 2 | N/A | 2.50-2.75 | 108 | N/A
    110/80 ZR 18 M/C 58W TL ContiRoadAttack 2 | 2.50 | 2.50-3.00 | 117 | 9.6
    130/80 R 17 M/C 65V TL ContiRoadAttack 2 | N/A | 3.00-3.50 |138 | 13.6

    (made the very large assumption that RA2 size/range specs are similar to the RA3. I couldn't find any data on the new RA3's)
     
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  18. egschade

    egschade Tuned and Synch'ed

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    If the RA 130 is actually 9mm narrower than the Demons does moving up to a 140/70 make sense?
     
  19. Godfrey

    Godfrey High Miler GT Famiglia

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  20. spowell

    spowell Just got it firing! GT Contributor

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    Continental 2015 technical guide: https://www.continental-tires.com/motorcycle/technology/technical-handbook
    Pirelli 2018 Tyre Guide: https://www.pirelli.com/tyres/en-ww/motorcycle/all-about-tyres/technical-data-book
    DennisKirk.com had the weights.
     

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