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Experimenting with tyres

Discussion in 'Modifications and Projects' started by Sir Skuffy, Jun 19, 2008.

  1. Hi All,

    I ride a GSX1400, thought I would get that in the open... :)

    I have been experimenting with typres a little. Three variations have been selected, all dunlop 209GP types:
    1). 180/55
    2). 190/55
    3). 200/55
    Now, I am not going to go into the technical reasons, purely my personal experience with these tyre variations. Remember, I run a 6" rear RIM and in all cases, 120/70 on the front. If you want to go into the physics associated, happy to do s0 - let me pull out my engineering degree and dust it off.

    Narrower tyre resulted in less of a "rounder profile". This resuled in the bike turning in quicker but did impact the lean angle and cornering speed. The back-end was a little skatier than I liked and did break loose more often than it should - yes, weight of bike and rider does impact this also. The tip-in was so quick I would sometimes be caught off-guard if I had not read the road conditions as well as I should. Tyre life was shorter also.

    Well, I thought I was in heaven. Still easy tip in (not as easy, but what is a 10milli-seconds) but not as exadurated as the 180/55 profile. Transitions from left-to-right was easier as less effort was required to bring it back over - so to speak. Tyre life had improved as did lean angle and corner speed. Tyre stability was higher and grip was vastly improved. Very happy.

    Well, this was an interesting experiment but thought I would try it anyway. The "engineering" mind tell me that it is not optimal, but reality does not always follow science until you analyse "after the fact"... anyway, not going there just yet... :)

    OK, the "initial" tip-in required a little more effort, but once over the pivit point, she slammed right down. Corner speed has increased as has lean angle. I have to exadurate the riding style a little to make it do as I wish - more peg weighting, more butt shuffling, etc..... Stability, a vast imporvement and grip, off the scale.

    What was most interesting was how much "tracking" through the corner had improved.... When on the 190/55's, warming the tyres was always fun, left/right/left/right and the outter boot would touch down... On the 200/55 this process required a little more effort, but once "in the groove" the transition from left to right was significantly smoother and felt more controlled. So, from my perspective, I felt more in control of the bike and the bike felt more planted to the road.......

    The larger tyre proved to be best suited to "spirited" riding and to those riders that are happy to move around on their bikes. If this is not you, you may well hate the tyre. What I also discovered was the improvesments in: Stability, lean angle, corner speed and tracking through the corner.

    To sum up, the bike felt more planted and more in "my control". Yes, some may argue we are not in control - in most cases that is correct. But, if I feel more in control and thus more confident I will be better prepared for that "oh crap" moment rather than being fearful of it.

    For me, this was the right move. :) Hope this is useful. If not, sorry for wasting your 3 minutes. :grin:

  2. Interesting inded. Logic tells me the front should be a bad match for the 200 rear. Any thoughts on a bigger front as well?
    What was the all up weight of bike & rider? The 1400 has about the same output figures as the Bandit (stock) but not sure of weight.
  3. Hi Two-wheels.

    The are limited fronts available that will match the "profile". A 120/70 gives you a taller tyre and then matches the "shape" of the rear. Going for a 120/60 would be better matched to say a 180/50 rear.

    Front and rear tyres need to have the same generic profile/shape. if not, then tracking and stability are effected. For instance, a flatter profile on the front and a sharper on the rear would result in vagueness in the front and greater possibility of the front pushing.
  4. nope i disagree with the whole bigger rear tyre. I ran a 190 on the sv for a while and it basically turned it into a drag bike.

    It was a pig to tip in, very slow, then once you did get it tipping in, it went from starting to tip in to completely on the side (maybe tyre profile had something to do with it too) but yeah there was no constant fall into the turn. Then trying to wrestle it back in the other direction, just made riding twisties not much fun and a lot of hard work, mid corner scares.

    Not ideal! :)
  5. Hey Stewy,

    Interesting comment on your personal experience. :)

    This past weekend, whilst following, did you notice how stable my bike was?
  6. Nice write up.

    I've been playing around with different tyre pressures and its slightly similar to what you've been saying.

    ie lower pressures more stable but slower tip ins. Higher pressures fast tip in but less stable/vague feeling.
  7. yeah actually come to think of it, it did look quite well planted....maybe it's the different profiles :?
  8. I've had some ok results with oversized tires on the rear in that the handling wasn't horrible. Still couldn't use all the rubber available though. I am not a fan at all of going an undersized tire for the rim.

    Generally I just like a quick turn in, consistent fall to full lean, and some stability on the edge of the tire. That generally means the right size tire on a modestly sized rim. I've tried the standard 5.5" rim that comes OEM on my bike, and didn't like it nearly as much as the 5" that I've got on now.
  9. Hey Stewy,

    Is about alot of factors:
    - Front and rear-matching
    - Tyre pressures
    - Bike specifics - weight, length
    - Riding style
    - Tyre compunds

    Dont worry, your not going nuts..... Each rider prferrs different types of tyres..... :grin:
  10. I run a BT002 180/55 on the Aprilia and have been looking for a 190/55 for a while. The 002's are rarer than hens teeth in that profile, so next time I'll plan ahead.

    I agree with the 180 comments. Turns in quick but you run out of tyre soon as well.
  11. It's worth mentioning that this experiment would need to be repeated with different tyre brands, as they're all of different shapes.

    Personally I value responsiveness and ease of steering at all lean angles to pure grip, and I get quite disconcerted if I feel a bike is "tracking" its line through a corner rather than doing exactly what it's told.
  12. Hey Loz,

    I think you mis-understood the term "tracking".... After tipping into the corner and wanting to go where you want it to go - tracking is good.

    Swift direction changes are best undertaken with some thought and a slight amount of effort as too many an in-experienced rider goes through the "oh bugger" moment and corrects incorrectly...... Many experienced riders also.
  13. +1 with Loz. I try and tune that "tracking" out of my suspension. I like it nervous. I think it's a preference thing rather than a definite plus point for the tires in the way that you describe it.
  14. Interesting analogy.

    I started to write a long response and then deleted it.... 15 minutes time wasted......

    Each to their own....
  15. Actually, I will respond :grin:

    I read motorcycle mags and the "Tests" sections. You know, the bike reviews and tyre reviews. As far back as I can remember they all talk about a good bike setup being one that "can track" well rather than one that is too loose.... :)

    I think the issue of "tracking" through a corner may not be understood by all. So, here goes........... A bikes ability to track through a corner infers that it goes where you point it and it does so with stability and does not deviate un-necessarily. So, when I pitch into a corner it goes where I want it to go.... If it hits a few bumps or ripples in the road - the bike-setup remains stable and it does not jump off of the path - a nervous bike will jump off-line. :)


    If you need to change direction, a stable bike that tracks well will change direction under your influence and in a more controlled manner.

    I have ridden bikes that are "nervous" and I have ridden bikes that are rock solid...... Nervous bikes are fun - expecially in the dirt. But, a stable bike will always be more controllable........

    Lets look at the Dirt side of the world - the top riders also want bikes that can track well. Once again, it infers stability and the bike to go where you need it to go.

    Look at it this way, pro-riders in street and dirt spend fortunes on suspension and tyres and... yes..... steering dampers..... Why, to be controlled and to track well. :LOL:

    But, then again, I may be wrong :eek: :LOL: :LOL:

    I know I know - suspension plays a major part - This is another looooonger story. :grin:
  16. All good. I too believe you may be wrong.