Despite the myriad of tire threads (pun intended), anóther one.
Having raced for decades, I started racing in ´the old days´ when performance rubber only júst started to appear. When Michelin made the first motorcyle racing rubbers available for basically just anyone (on special order) that was a sensation.
It was very quickly learned though that the racing compound only worked when on temperature and below that was wórse than the off the rack touring variant.
That was about half a century ago and this has not changed.
Yes compounds have evolved a lót but the principle of the temperature ranges applies the same now as then.
For sporting rubbers, especially the street legal track ones, the warning múst be heeded. They are nót designed to work under cold conditions.
Now, some may have a lower limit of 10 degrees, other 0 and some even lower. The much celebrated AD08(R) is rated to work at relatively low temps.
The moral of my post is; FIND OUT THE LOWER TEMP LIMIT!!
(https://myalbum.com/photo/9UWweKCOTIGo/1k0.jpg)
p.s. this is a warning with a modern sports tyre for sale nów.
Oddly enough I just posted something similar to this.
The AD08Rs are very very noticeably worse in cold. Which is starting to get on my nerves after years
Noticing this more, now in the 3rd season.
Very impressed the 1st year. Last year, hmm. This year marked diff.
Quote from: shnazzle on January 11, 2019, 11:24
Oddly enough I just posted something similar to this.
The AD08Rs are very very noticeably worse in cold. Which is starting to get on my nerves after years
And the AD08 has a lower range of -10 whic is about 10 degrees colder than most, p.e. Toyo´s sport wubbahs. Go figure.
Another VERY important ´detail´ is that sport rubbers age rather a lot faster; i.e. loose their flexibility = become less tolerant to lower temps over time.
Same goes for the number of ´heat cycles´ although that has a different effect; the whole temp range becomes narrower after the tyre has been heated up a lot x number times.
Oh and óverheating them means they have become rubbish.
Anyway, the lower limit is a thing to watch.
Have look at the Yokohama summer tyre catalogue and you till notice that the AD08 and A052 come with the temp warning. The Fleva, Sport and Sport105 do not.
All this means that the heralded supersports rubbers are best not used during the colder months. Never mind the rain; that is not the crucial issue; the temperature is.
Even for me over here; go figure the UK!
I like the AD08Rs on track, but find the sidewall very stiff on the road; and to be honest the extra grip isn't really a plus point for me for road use. Horses for courses...
Quote from: james_ly on January 11, 2019, 13:33
I like the AD08Rs on track, but find the sidewall very stiff on the road; and to be honest the extra grip isn't really a plus point for me for road use. Horses for courses...
My point is that ´the extra grip´ only exists when the rubber is at temp.
Under that, that is LESS grip then with the mundane general use ´sporting´ types.
That observed, once on temp more grip is of use for everyone if you happen to need to emergency stop. The latter is the only reason I am looking to replace the current El Cheapos; them sliding is rather fun; the knowledge they offer same lack of grip when braking is less so. This also applies to road legal track rubber running cold, which makes the circle round.
Oh and don´t read it for just Yoko´s; as I wrote earlier they have a lówer temp. limit than most competitors.
Quote from: Petrus on January 11, 2019, 12:41
And the AD08 has a lower range of -10 whic is about 10 degrees colder than most, p.e. Toyo´s sport wubbahs. Go figure.
Another VERY important ´detail´ is that sport rubbers age rather a lot faster; i.e. loose their flexibility = become less tolerant to lower temps over time.
Same goes for the number of ´heat cycles´ although that has a different effect; the whole temp range becomes narrower after the tyre has been heated up a lot x number times.
Oh and óverheating them means they have become rubbish.
Anyway, the lower limit is a thing to watch.
Have look at the Yokohama summer tyre catalogue and you till notice that the AD08 and A052 come with the temp warning. The Fleva, Sport and Sport105 do not.
All this means that the heralded supersports rubbers are best not used during the colder months. Never mind the rain; that is not the crucial issue; the temperature is.
Even for me over here; go figure the UK!
Pretty sure I'm sensing what you have described.
Age (fitted feb 16) 3rd season. Still happy with the rears, but frontend is nowhere near as direct as once was.
Right had some time to look into it again today.
As I said I have doem a lot of racing over the years and am aware of the vast difference in operating temperatures between racing and road use.
As a perspective: F1 rubber works between 90 and 130 degrees Celcius, typically with a 20, max 30 degree band width. The softest compunds in the lower range, the hardest in the higher.
The barely legal, well only in name legal but even by Nankang nót advised for road use, AR-1 operates between 70 and 105 degrees celsius. It is easy to grasp that on the open road it is a challenge to get to 70 degrees when the tarmac is >20 degress even, never mind 10 degrees and moist.
With this light shining on sporting rubber in winter the ´under par´ grip is logical and not réally under par but true to spec., just not meeting expectations.
Now the tricky part is the ´hard´ bit. Hard racing rubber is not directly comparable with hard wearing street rubber. The latter one will totally overheat, overcook when raced on a mildly nice day yet be ´hard´ concerning little grip.
The thing to understand is the optimum working temp for a specific rubber compound; the temp. range where the wear rate crosses/coincides with the grip curve.
For road use tyres the wear rate needs be wayWAY lower than acceptable for track use and the optimum grip delivered at way lower temperatures.
Again referring to Nakang the NS-2R is a good example as it comes in a ´track´(120) and a ´road´(180) compound.
The latter is harder wearing yet has a lower temp range for the operating range.
See the ´hard´ confusion? Typically a harder racing compound ofers the max grip at hígher operating temperatures.
So, where the road tyres meet the track tyres the terminology falls short because where the two ´hards´ meet has shifted.
In the 1980s I raced a lot (motorcycle) with the Dunlop KR124. It was available in a various compounds and the softer ones worked great in the rain on road circuits. They did not work for road use. You just could not get/keep them on temperature.
They would wear quicker because soft yet not offer the expected grip because not getting into the operating range.
Same thing track rubber for cars on the road even though DoT or E rated.
So, there we have it. To talk the same language we need to compare the same types of products. This is more challenging than it seems as manufacturers are amazingly obtuse in their information and with the road legal track rubber rubbing shoulders with summer road rubber the matter becomes ... as tacky as overheated rubber.
The DoT or E rating simply means that the tread meets legal requirements for use on the open road. It means nóthing else. It allows you to get to a track on a racing compound. It will not offer near optimum performance on the way.
My appologies for preaching to those who are already in the know.
I did not know and very informative post. Thank you!
The only "Race" I've ever been in, and there are some that would argue with that, is the Human Race. But nevertheless I do like to be aware of things technical and I found the post by Petrus to be very interesting.
Quote from: Joesson on January 15, 2019, 10:10
The only "Race" I've ever been in, and there are some that would argue with that, is the Human Race.
Still very easy to imagine the abissmal difference between flogging it on the open road and a race. Have a look at Isle of Man TT races.
The track is pretty normal, representative road conditions. Now compare driving with traffic, speed limits, et al versus closed road no limits but the conditions.
You´d be flying, literally, at top speed with the MR versus how fast do you dare with the chance on a lorry on half your half around the corner.
Near us there is an amazing road and a large tract of that is a special stage in the Rally de Montes de Málaga. With the road closed the world changes. Éverything changes. Driving fast is not in the same order as thrashing it on closed roads.
Not hard to imagine that with such a changes in circumstances, shift of the limits, that the forces on the tyres increase.
Bear in mind that the kinetic energy is related to the square of the speed = the forces on the rubber increase exponentially. Those forces equal heat in the tyres. See? Easy no?! ;)