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What affect a wider tyre?

Discussion in 'Riding Gear and Bike Accessories/Parts' started by removed-6, Sep 18, 2007.

  1. Can someone explain to me what affect would putting a 190 rear on my GSXR600 that has a 180 as standard have?

  2. Theoretically, a higher profile, steeper sides and a sharper centre if fixed to the same width rim. Quicker turn in and slightly greater side grip. To be honest while I felt a difference when I did this, I got used to it pretty quickly and forgot about it.
  3. So they are all positives Loz, any drawbacks? Thanks..
  4. Well, it changes the handling a bit, easier turn-in means less stability - and a pointier contact patch means the centre wears out quicker. But it's all by small degrees. Try it if you like, see if you get anything out of it, personally I've gone back to 180 rears.
  5. Depending upon the profile of the tyre, I have a 190 on the bird rear and find it tips in slower than the same tyre in a 180, and transition from one side to the other is more of a wrestle.

    I use Pilot Power rears.
  6. I'm actually thinking for the track bike so the centre wearing out is not really an issue. When you say less stability, do you mean when stood up or tipped over?
  7. I asked the same Q and was told the same. It would slow the "turning" of the rear.

    I too use Pilot Powers, awesome tyres :)

  8. Yes, an over-wide tyre will not give correct curvature at the sidewalls, causing the bike to want to stand up in corners. If you go to a wider tyre for racing use, you will usually have to raise the rear ride height to compensate so that the bike tips into corners properly. I have tried this, but the only
    benefit was that I could then use common 180 tyres instead of wierd rare 170 tyres that the bike was designed for.

    I reckon keep your 180 tyre size. If you want quicker turning, raise the rear ride height. If you want more grip, adjust tyre pressure.

    Disclaimer: changing the geometry and handling of a bike could make you have an accident, especially if you are a nuffy. It may also be illegal for street use???
  9. I have raised the rear ride height by 6mm to assist tip in and transition. On a bird, 6mm is a notable difference.
  10. Is that 6mm at the shock or 6mm at the axle?

    I raised my FZR1000 by using 3mm shorter links, which lifted it at the axle by about 35mm. In combination with a 180 Pilot power, it handles great.
  11. I think it is valueable hearing everyone's experiences on this matter as we all benefit from knowing. In my opinion I think that there are different results depending on tyre brand/model and bike/suspension setting, let alone rider preferences.

    I will give my feelings from my experiences but this subject is no way cut & dry in an answer.

    I truely believe that any tyre change from standard, including same size, different brand is an experiment that can work for some and not for others.

    In the past, on a 5.5" rear rim, I have tried 180's and 190's, finding the 190 to give noticeable more traction in slower speed corners but induced a weave (low frequency wiggle from the bike) in higher speed corners. So in my past I have opted to use a 190mm tyre at Winton & Broadford and a 180mm at Phillip Island.

    Some tyres will be distorted if squeezing a 190 onto a 5.5" rim, causing a smaller contact patch when the machine is at half lean angle and also altered carcass flex affecting ride and hence traction.

    I prefer to run 190 tyre on a 5.5" rim rather than a 180 on a 6" rim as I feel a 180mm tyre on a 6.00" rim will have a wider contact patch when bike is vertical affecting the 'self steering' behaviour of the wheels which I do not like.

    Now, all that being said, I have found that not all tyres actually measure up at the size that is written (moulded) on the side wall. I have used Michelin 18/67-17 slicks that actually measured 195mm wide even on a 5.5" wheel! This Michelin was superb on a 5.5" wheel, infact I preferred it on 5.75" wheel but terrible on a 6.00" wheel. I think tyre design has changed a lot over the years and they are now catering for the wider rims.

    (Edit) The width & shape of a tyre will be altered depending on the aspect ratio (side wall height), a higher profile tyre will blow out to a wider width and a lower profile not measure as wide when fitted and an altered tread profile accordingly.

    I actually believe that a 5.75" rim is the perfect size, many MotoGP and SBK teams actually run this size, a fact I have seen in the paddock at Phillip Island over the years.

    I do really like to hear what works for each individual, I think we can all benefit from all the feed-back, it is like a GP or SBK rider needing another rider in the team to hone in on the perfect setting much quicker, 'Team Netrider'...... gee maybe the tyre companies could learn from us?

    Hope all of that is understandable :grin:
  12. Irrespective of rim size, the wider the rim the slower the turn in. Yes the tyre shape influences this but all things being equal the rule applies. Stick with the OEM size
  13. On the near stock '98 R1 that I raced at Daytona, I actually had the rim narrowed from 6.00" to 5.50", all riders were jacking up the back of their bikes in an effort to make it carve a tight line on the infield but the instability over the fast bumps made the ride height a compromize. My bike was rock steady and carved a tight line, I finished 4th only beaten by GSXR750 full Superbikes.

    It was a CCS 145hp class, the smaller engined bikes with the same horsepower were so much more agile in the corners.
  14. Whoops I meant tyre not rim. The wider the tyre the greater the distance from the centre to edge so the more the bike has to "lift" (yes against gravity) in order to use all the (rear) tyre when cornering (greater distance between centre and edge of tyre on front vesus rear).
  15. Actually I think that a both a wider rim and a wider tyre will do as you say and move the contact patch further away from the centerline (I feel we've touched on that matter recently in another thread?), I agree that in most cases it is not the best for sweet, confident handling.
  16. I always understood the conventional wisdom to be that the wider tyre slows the steering a bit, but you have "more" rubber to put the power through.

    The 9R came OEM with a 190 rear. It steers fine as far as I know... haven't ridden many other bikes though.

    I've heard of guys dropping the triple clamps a few mm to quicken up the steering on the 9R though...

    This question was asked of spanner man a few years ago and his advice was basically that the engineers are smarter than us. They've already worked out the best logistics for the design of the bike so better to leave well enough alone... meh.
  17. But they didn't design the bike purely for the track, which I am using it for, and they are governed also by their bosses and the accountants.
  18. 6mm at the top of the shock, haven't measured the change in height at the axle.