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Tyre Pressure - Based On Bike/tyres/both?

Discussion in 'New Riders and Riding Tips' started by Coco., Nov 20, 2012.

  1. I'm running Dunlop GT501s on both front and rear of my Suzuki Across. Stupid tyres for a learner, but they came with the bike. I'm looking forward to a good pair of sports tourers when the time comes for a new set.

    Suzuki recommends Front 29 / Rear 33. Does this depend on the tyres you're running? I'm finding that mine are a bit sluggish and tend to follow the profile of the road (e.g. in dips, ruts and vertical curves). I figure a higher PSI might remedy this, but I'm a noob and don't know any better.

    Any PSI recommendations for this bike/tyre combo?

  2. Unless you are using something weird or ancient then use the bike manufacturers recommended pressures.

    Check your tyre pressure guage for accuracy if you think there may be something amiss.
  3. I'm not sure about the best pressure to use on a 250. However, if you haven't already got one, get yourself a good quality tyre pressure guage and make sure your pressures are as per the manufacturer.

    Once you've done that and ridden for a while, try changing the pressures (up) by 2 to 5 psi and see if it makes a difference.

    To give you an idea, Suzuki say that I should use 36psi front and rear on my 1200. However, I've found the best compromise between comfort, performance and tyre life is to have the front at 38psi and the rear at 42psi (except in summer when I drop each by 2psi)
  4. Raising the tyre pressure above recommended may reduce the tyre contact patch especially under braking.

    Judging pressure adjustments via subjective 'rider feel' is at best dodgy and at worst dangerous. Unless you have access to specialised technicians experienced in tyre testing then using the manufacturers recommended is a better plan for everyday street usage. Specialised sports may recommend dropping pressures under specific circumstances.

    If your days journey takes you across extremes in temperatures and / or altitudes then it would be worthwhile checking and adjusting as necessary at various times during the journey.
  5. No such extremes, Fractalz. But I think you may be right about dubious pressure gauges, b12mick. I had a fumble through previous threads on the topic of tyre pressure and the matter came up again and again.

    I will definitely be investing in one as soon as I free up some cash (Xmas preparations always see me destitute). In the mean time, I won't put so much faith in service station pumps with broken nozzles and flickering pressure reading displays! ;)
  6. I'll tell you how.

    I read somewhere, can't remember exactly where, that the easiest way to find out if your pressures are reasonably accurate is to check and set the pressures when the tyres are cold (slightly obvious) then ride for an hour to get them warm and check them again. The change in pressure should be around 10% higher. If the change is more then your pressures were to low, if the change is less then your pressures are to high.

    Using this method I confirmed my subjective 'rider feel'.
  7. I have Pirelli Sport Demon front and back on my Across. Running 32psi front and 34 psi rear (cold). Recommended is 32psi front and back from the mechanic, but I found running a higher rear felt much better.

    These tyres are more sports orientated, but are classed as sports tourer I think. Either way, it grips well through the twisties giving me enough confidence and commuting on them has seen no issues. I have done 17000km on them so far, front is still in relatively good condition, rear however may need replacing in a month or so due to squaring off. Only cost me $325 fitted for the set so can't complain!
  8. STEAL!
  9. I'd considered slippage from cold tyres as a cause. But I came back after an hour-long ride in warm weather on Sunday and rounded a very familiar bend that confirmed my suspicions about it being something else. I could feel it sliding into the curve of the road and slipping into linear ruts.

    I took her out for a spin just before and checked the tyre pressure at a servo (which read 29/33) and can't tell if I'm going crazy, but the bike felt really loose in the straights - particularly up front.

    I'm going to check the front over with a torque wrench to make sure everything's tightened according to the manual. Don't want to rule out the possibility of play in the head tube or forks.

    I'm getting my guy to take her for a spin this evening, just to make sure that I'm not going loopy. :confused:
  10. It could also just be the tyres themselves.

    When I first got my Bandit (from new) I had it back in the shop every couple of weeks for the first 2 months, while they tried to work out why the front end would wobble and shake it head under some circumstances.

    Finally, one of the parts guys looked at the front tyre pointed to the tread pattern and said "There you go, there's the problem, those grooves down the centre of the tyre is causing the problem. Replace the tyre with a different tread pattern and you'll be right". He was 100% correct. I replaced the Macadam (only 8000km old) with a Metzler M1 and it transformed the bike.
  11. oh yeah ... the 10% rule of thumb is a good and reasonable way for us laypersons to attend to the matter. Bear in mind tho that a person has to have a starting point and the best place to start IMHO is the manufacturers suggestion as it is usually pretty darn close.

    Tyre wear can cause same strange effects. Nothing nicer than a new set of rubber.
  12. And that is exactly what I suggested in my initial response.

  13. I up the psi if I'm loading the bike with mrs and luggage, but we are talking 3 psi, not 10 or something lol. I do notice the difference too.
    • Like Like x 1
  14. oh yes I agree with that ... but you started warbling on about your Bandit (darn nice bike that - they go like stink:)) The exact psi that you use in your Bandit is a bit irrelevent to a 250.
  15. I wasn't warbling, rather I was merely using it as an example of how using the motorcycles manufacturers recommendations may not actually be the most suitable.

    In fact I said "To give you an idea......." that would indicate to most people that the writer is giving you example of what they mean.
  16. I've seen your missus in the "Are you hot?" thread - I bet she'd hardly warrant more than a nominal increase (nice work there, by the way ;))!
  17. ah yeah but then some people may think you are saying "put 42psi in it" ... don't laugh ... I've seen it happen :banghead:

    But anyways, I luuurv a good tyre thread ... strange no one has mentioned yet to the OP to make sure and change to summer air :D
  18. Elaborate for me? :confused:
  19. I've also seen people run as low as 20psi on the road, because that's what a mate who does track days uses.

    And, damn I knew there was something else I had to get done at the next service.