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Does cold road temperature affect tyre grip?

Discussion in 'Technical and Troubleshooting Torque' started by Mouth, Oct 30, 2015.

  1. Yes

    14 vote(s)
  2. No

    5 vote(s)
  3. Maybe (I'll discuss my reasoning below)

    1 vote(s)
  1. Interested in what the general consensus is on whether cold road temperatures impact the grip on street motorcycle tyres under normal riding conditions? (Street tyres being those tyre types below track and hyper sports).

  2. Does the pope shit in the woods?
  3. I'm guessing you're saying Yes? What's your reasoning and logic/hypothesis for that?
    • Like Like x 1
  4. I haven't looked into this topic but all else being equal I suspect the only difference between a cold and hot road would be notably faster heat transfer away from the tire, maybe a localised cold spot on the contact patch. The effect would change based on the compound, and for most street tyres would make little to no difference.

    In reality though a cold road often means a cool breeze, maybe some earlier rain, no direct sunlight, etc and depending on the riding being done the tyres might not get up to optimum temperature or take well longer to do so, decreasing available grip in the meantime.
  5. elastic modulus... chemical adhesion... not difficult to figure which way it goes, but enough to make a noticeable difference for the kind of riding done on those tyres?
  6. Been through the Snowys when it was close to zero,didn't notice any slippage,shrinkage yes,slippage no.Thats pushing on a far bit with a bunch that do the same. To be honest I get more slippage when its very hot,40 plus
  7. I ride all year around in Melbourne and can feel the difference in grip when it warms up.
  8. Hmmmm... I always slow down riding to work in the early morning but mainly due to frost and wet patches on the road. Most of my riding is on 60. -70 km twisty country roads for 10 mins or so till I get onto a highway. Have found this on Internet. www.tyresafe.org - Winter Weather Tyres, tyre safety advice for winter from TyreSafe I d like to think that pressure effect would greatly impact your grip. So what's the difference between a soft and a hard tyre? How does pressure change or how are tyre threads affected by difference in temp? For my neighbourhood, temps can vary as much as 30 degrees from sunrise till midday. Would be interesting to get some factual answers.
  9. That's what I'm thinking - for normal riding with street tyres, it would make no difference or insignificant difference.
    Because the heat produced from friction of rubber against a cold road would be much lower than the heat produced from a normal or high temperature road?
    I find it difficult to accept - I'd like to see a study showing that.
  10. Or it's your confidence and mood that changes with the season?
  11. Unfortunately, that's about icy and snowy roads with a difference in stopping difference between summer and winter tyres. Not relevant to this question on road temperature.
    Yeah, that's what I'm hoping we can find.
  12. The friction produced shouldn't be dramatically changed, but the temperature differential will cool the tyre faster even while in use - requiring more friction to keep the tyre at operating temperature. Unlike your bikes motor, tyres don't have a thermostat to regulate their temperature. These factors all contribute to changing the rate of temperature change, and since we know most heat is generated through braking and accelerating on a bike tyre, a long straight road in 9C weather isn't going to be confidence inspiring coming into that first corner.
  13. But it's the internal air temperature within the tyre - which itself is highly dependant upon the air pressure within - that holds and transfers the heat to the rubber. The reason why nitrogen is often recommended for tyre inflation, since nitrogen is a cooling agent and helps to stabilise the air temperature within your tyre.
    I wonder, that for a normal tyre in normal conditions, does the outside cool air temperature and cool road surface temperature, have such an insignificant contribution to the heat from friction, that the internal air temperature of the tyre and the temperature of the tyre's rubber is not affected by the cool or warm outside temperature or road surface temperature (once the tyre is initially warmed-up from rest).
  14. Plucked this out of my arse but I don't think heat has anywhere near the effect on the grip of road rubber, track rubber yes but not road rubber. Never heard of cold rubber road crashes, yes it would be interesting to have some tech data on this. Never see any on the tyre manufacturers sites.You would think it would be front and center if it was an issue.
  15. If you are riding on the track and pushing to the limit, temperature makes a difference but sensible riding on the road it is not an issue.
  16. Let's' not forget that bitchumen itself changes quite considerably due to heat.
    Standard road tar becomes more pliable and extremely sticky under heat stress.

    Perhaps it's the road griping the tyre more than the tyre gripping to road in these conditions.
  17. Yes, but in this scenario/question I'm talking about cool vs normal road surface temperatures having an impact on tyre grip. Not extreme road surface temp causing bitumen to melt.
  18. Although for an ideal gas, our atmosphere follows the same principles in this case - PV=nRT. In a tyre, the temperature (T) will change based on heat transfer from the rim (brake heat, temperature, IR radiation) and tyre (internal and external friction, IR, temperature, conduction from road surface/rain/contaminants) and is the main reason pressure (P) will increase, because the volume (V) of the tyre will generally remain constant excluding track level turning and acceleration. Nitrogen is simply closer to an ideal gas than our 21% odd O2 atmosphere.

    The air in the tyre doesn't generate any heat (I'm sure there is some small force at play which does, albeit practically immeasureably) in the grand scheme of things, but I'd be interested to be proven otherwise. It will simply begin to heat up (and increase pressure) as the inner layer of rubber and rim is warmer, and cool (and decrease pressure) as they cool.