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Discussion in 'New Riders and Riding Tips' at netrider.net.au started by junglist, Nov 25, 2008.

  1. I went for a short trip in to get some lunch and on the way back had the back slip out at low speed under mild acceleration while exiting a roundabout.

    It gave me quite a rush and was pretty controlled, but even in the wet on the daily commute havent had so much movement in the rear.

    I had a look at the patch of road and it was quite new, quite even rolled bitumen with no wet patches and no oil marks.

    All i can think it may have been due to is cold tyres, or, maybe the compound is degrading/has degraded?

    The other thing is i've got a few 5-10mm long cracks in the tyre towards the middle of the tread. It looks like the stresses of acceleration and breaking are causing these fractures, which then extend under cyclic loading. Is this normal?

    My own feeling is that it's a sure sign of shitty rubber.

    They are Dunlop SportmaxII
  2. cold tearing. Pretty much a sign of a shitty rider ;) I assume that the tyres are new, given the age of the bike.

    go easy on them for the first few km and don't run your pressures too low.
  3. There's ya problem right there.
  4. damn loz you beat me to it again
  5. i have no option but to go easy for the first few kms every ride because i have to traverse a string of 40/50km/h zones and ride through some expectant speed traps.

    so what am i doing thats wrong? i would have thought the tyre should lose traction before the it cracks. :/

    as for pressure, they are running a few psi higher than the recommended and i check them regularly.
  6. yep, the dunlops get a pretty crappy wrap, but they are the OEM tyres with the bike.

    would a pirelli strada be a big improvement or would i need to go to a diablo to notice any real difference for the better?
  7. Wrapping your rims in old scarves and gaffa tape would be an improvement.
  8. Dunlop tyres, aside from the GPRA-10's for smaller capacity machines, are almost universally crap in my opinion and experience. If a Dunlop tyre offers comparible warm grip to a competitor's tyre, then they'll wear out twice as fast, and take three times as long to warm up, and be slippery as crap in cold/wet weather.

    Pirelli Diablo Strada's, or Michelin Pilot Road 2CT's, would be what you're after. Heck, on a small bike like a CB400, I'd even stick Pirelli Diablo Rosso's (for absolutely superb wet/cold weather grip) on it, and despite them being softer sporting tyres, there's not enough weight/power to wear them out quickly, and you'll likely get >10,000kms out of a set and never have a slip again.

    Also consider the Conti Road Attacks as well.
  9. You know more than I do from experience I guess, so I'll take your advice at face value. Is 6000km new?

    TBH this is my first set of motorcycle tyres, but I'm expecting that they are more than half gone given the information I've gleaned from the wisdom of the internet (to date).

    Cheers for the advice. :beer:

    This was what info I'm after. The guy at the bike shop was just short of laughing at me when asked about the Rossi's for the 400...
  10. i've had pretty much the same response when asking about sticky tyres for my VTR250. when im in my zone, i ride the balls off it at times. i'd rather something stickier than my BT45's, which although an excellent tyre, im sure i can get better.

    when i get the licence back, and some money, i'll be getting some GPRA-10's i think is what im after.

    bugger what the shop guys think, get the tyres YOU want, and think would suit you better :)
  11. Your tyres will need to be rated to the correct speed rating for your bike. Someting designed for a GSXR-1000 etc will not get any temperature in them on a little 400, even if you're called Casey.

    Sport tyres are Ok on the track but will be slower on the road as you can't sustain the temperature in them needed for them to work at their best. Get a good set of road tyres, not "track" tyres.

    If your tyres are cracked after just 6000km, you should go back to the dealer as it appears to be a warranty issue - unless you've beed riding with them seriously under-inflated all that time.

    They're probably a lot older than the bike. Look at the side wall. There should be a four digit code in the letters/numbers after "DOT". The first two number are the week number, the second two signifies the year the tyre was made. eg. 3204 means week 32 of year 2004. Don't use tyres over 3-4 years old.
  12. Only if you're referring to the barely legal road tyres which are just race tyres that happen to have tread. Apart from those, sport tyres will warm up faster and offer better grip in all situations, vs. hard touring/sport touring tyres - as a generalisation.
  13. Some truth in that but a bit off the mark.

    Indeed, you need to be wary of putting certain tyres on light bikes (and it is the weight of the bike that makes the big difference, not the horsepower), but the CB400 is hardly a ballerina.

    And true, some of the proper race tyres that have been homologated for road use simply so they can be used in superstock type classes aren't so hot for regular road use. They have limited heat cycles like a slick and don't work unless at full temp. The rest are good to go.
  14. As a good all around tyre that sits just below the rosso that Stew mentioned are the Corsa III's...very close to the rosso, but maybe a bit better for day to day riding and commuting. Although either would be suitable, I reckon. You could even go the Strada if you want something harder again for longer life with a little less grippiness.

  15. You'll like the Alpha 10s, they rock on the Spada.......they do wear very quickly though, no good if you spend much time in a straight line.

    As for CB400s being light, aren't they around 200kg wet?,that's not really any lighter than any modern sporty sub 1000cc bike these days
  16. If you keep the tyres at the recommended pressure (or slightly above, I would be taking them back to the dealer.

    If they were seriously underinflated for a time they would show signs of underinflation (scalloping etc).

    as for tyre choice, Im a big fan of road pilots and battlax's. Not as grippy as something like diablo's but they are a good balence between grip and wear.

    Another thing to consider, its been my experience that a sports/touring tyre will give you a bit more warning when you start to stretch the friendship a bit. The diablo's I had on my FJ1100 stuck like shlt to a blanket, but when they let go......... they let go big time.