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Larger Tyres

Discussion in 'Technical and Troubleshooting Torque' started by Nynn, Sep 30, 2015.

  1. Hey Guys,

    I'm sure someone here can nudge me in the right direction here.

    I purchased a 2nd hand bike for my partner last month for her birthday and all has been going well until she had a bit of a slip of the back wheel going around a round about.

    Apparently it has happened a few times but never when i have been riding it.. but anyway. She is now refusing it ride it and has been riding my bike instead until i replace her tyres.

    She has a 2011 YZF R15 v1.0

    He main issue and i believe it is more of a visual issue is that the rear tyre is just so skinny.

    The Question:

    Whould it be wise to put wider tyres on the bike assuming they fit. Ive did a bit of looking and it seems as though i can replace the rear standard 100/80-17 with 130/70-17 without too many issues. But im defiantly no expert in tyres.

    Or would it simply be better to replace her slightly worn tyres with a pair of grippier tyres which may pose the same safety concerns regarding the size?

    Current Setup (Stock)

    Front Wheel
    MRF Zapper 90/80-17'' on a 1.6 RIM
    MRF Zapper 100/80-17'' on a 2.15 RIM

    I would appreciate any knowledge or opinions on the matter. (ill upload a photo after work)
  2. I have a 3.00 rear rim and I use a 140 tyre. Thats borderline to big a tyre for that rim but the bike has a lot of poke.
    The std size tyre for a 2.5 rim is a 120. Going bigger pinches the Tyre and deforms the profile,not good. I would be looking for a tyre with more grip rather than bigger. Start searching the know brand websites, Pirrelli Dunlop Bridgy ect for what is available for that rim size,probably 120 and less and bike in a performance type Tyre and then talk to a good shop that does lots of tyre fitting.Do the research before going to the shop,it pays to get educated on whats available.
  3. Go with better tyres in the standard sizes. Wide tyre=better grip is a fallacy. Crappy tyre (and many OEM tyres are quite crappy, particularly on small bikes)=crappy grip is a fairly good assumption. The only valid performance reason, IMHO, for going up a size is if there are simply no better ones available in the correct size.
    • Agree Agree x 2
  4. When u say it slipped, did she crash? I'm just wondering if your partner is sure of what's happening. It'd be strange to have the rear stepping out on such a modestly powered bike IMO
    • Agree Agree x 2
    • Like Like x 1
  5. No crash. As I said I haven't experienced it but she tells me it happens all the time... I think it's more of a mind set for her I think.

    Thanks for the I site patb and Zim. I might just go to the shop I get my bike services and see what they think.

    I think the larger tyre may effect the handling and may end up being worse off.
    • Agree Agree x 1
  6. Agreed with Darren. Was it wet? Was she riding the rear brake or downshifting?

    Maybe buy her new tyres (same size) to get her back on the bike, but she really needs to figure out what is causing the feeling of a slide (I doubt it's a real slide). Any tar snakes on the roundabout?

    Can she get tuition?
  7. go sit (or follow) and watch her going around the roundyroundies, see what's up

    alternatively, does the V2 R15 wheel fit? it comes with 130 wide tyre..
    • Agree Agree x 1
  8. Nah look she was just backin' it in on the brakes and power slidin' on the way out.
    • Funny Funny x 1
  9. Not a fallacy depending on the application. But I agree in this instance just get better tyres in the same size.
    • Agree Agree x 1
  10. are you heavier/lighter? Is she more aggressive on the throttle? Has someone put some tyre shine, or are they the original tyres that came on it?

    Is the rear shock adjusted or crapped itself?

    Are you taking the same line through the same round about?

    There's lots of things to consider in regards to this stuff. if the tyres are 4 years old(or more likely older) then that could definitely be a factor.

    Are they Shinko's on it?
  11. Apart from the simplicity of just getting much better tyres in the design size, there are some considerations one much make in going oversize, such as Zim has provided in his explanation of how a wider tyre on a thin rim affects the tyre profile.

    Here are a couple more. Tyre clearance within the swing arm - often a larger tyre will have trouble clearing such things as chain guards, and the little loops that secure drain tubes. Tyres do change their shape a little in use and real close clearance - less than 10-15 mm is not a good idea. I wondered what those marks were on the tyre once.

    A very large difference in front/rear tyre size can introduce handling issues which some might find uncomfortable. I had a modified bike with a 100 on the front and a 140 on the rear. It did hang on beautifully on roundabouts and tight corners under power, but on the open road, the rear wheel would "track" grooved surfaces, such as those made by heavy truck traffic oddly, and crossing rollover curbs at shallow angles was very interesting. A laid back attitude towards control in these circumstances was useful. The problem was caused by the rear tyre "climbing" the incline before the front. It also tended to "dive" into corners. I changed the wheels and tyres to 100 front 120 rear (stock) and the "vices" went away. Now corners as if on rails, grooves and ridges don't give the bike the "wriggles" out on the road, and rollover curb at shallow angles are just the little bump without the large weave in the wrong direction it was with the non-standard wheel set.

    Fair swap, lose the vices for a little less "stick" under acceleration on tight corners. Put your trust in the design engineers.

    I agree heartily with the OEM tyre criticism, Tyres vary hugely in the amount of adhesion they provide. Buy the best tyres which suit the sort of riding you do that you can afford, bearing in mind the tyre life vs adhesion tradeoff. Look at riding style. Let it go at that as a first step. Roundabouts with steep cambers do provide certain challenges to motorcyclists.
    • Informative Informative x 1
  12. Buy some grippier tyres in the same size. Michelin pilot sporty are listed on the Australian Michelin site and I believe these tyres will be much better than the OE tyres. Pirelli list a MT75 in those sizes too.
    Plus if this bike is a 2011 model with the original tyres, they may be a little hard any way.

    I used to own a Honda CB125E with Kenda tyres. Did 6000km on those crappy tyres, then changed to Michelin M45 (same as on postie bikes).
    Made a huge difference to my confidence in the way the bike handled and gripped the road.

  13. All good advice above. No-one has mentioned tyre pressures though. Check tyre pressures often strange handling can be caused by wrong pressures.

    Unfortunately now it has become a psychological hurdle to overcome. Narrow tyres do get caught in road tar snakes and grooving more readily than wider tyres.
    • Agree Agree x 1
  14. I've been down this road (pun intended), and decided to stick with the OEM sizes.
    Cars may benefit from a wider tyre, most bikes will not, is what I know believe.
  15. A wider tyre will not be the solution. Engineers put a huge amount of effort in working out the size of tyre for each bike. Changing size will more likely make things worse. Good tyres in the original size will work much better for the design of the bike. Check the owners manual for the correct size and make sure the tyre pressures are correct. One last thing, riders can induce slides in bikes due to poor technique, mostly from gripping the bars too tightly. Also make sure your partner is riding with a good technique. This all assumes that there was nothing on the road surface like coolant, petrol, diesel etc
    • Agree Agree x 1