Different mixes will give different temperatures but on average it seems that kart tyres are designed to give maximum chemical adhesion at about 60C.
Thats the same temperature as your central heating provides for radiators, and too hot to be comfortable to put your hand on.
In current conditions, you are probably going to struggle to get your tyres up to that temperature because the track is probably only at about 7C at the moment, while in mid summer the track may be well over 30C.
Putting the pressure up is not going to help much because you can quickly go outside teh working range of the tyre. Thats the point where the air pressure makes the tyre so 'stiff' that it doesn't flex the amount necesssary to get 'work' done (the heat comes from retained energy from the 'work' done to the tyre) and the contact patch shrinks because teh kart is balancing on the dome of the tyre rather than a patch right across the tyre.
When measuring your temperatures you should measure at several places across the width, it the temperature is elevated at the sides, you are running under pressure and if it's elevated in the middle, then you are over pressure.
Of course, take the track into consideration. If you have just come out of a hard corner, the tyre is likely to be hotter on one side.
Take the temperatures several times with a stop watch. If the temperatures drop a degree evry five seconds, then you can get some idea of what the working temperature was.
The pressure will go up as a constant (if we ignore the change in volume). old Pressure / temperature in Kelvin (add 273 to Celsius) = new pressure / new temperature.
So if your tyre pressure was 1 bar, tyre temperature 10C on the grid, and your tyre temperature was 50C on the track, your pressure should be 1.14 bar. (1/283=0.003534; 323* 0.003534=1.1413)
If you got the same pressure rise starting off with a higher tyre pressure (ie, you went out at 1.14 and got a 0.14 pressure rise to 1.28 bar, and your starting temperature was 10C then your tyre temperature on track would be 47C, ie colder). If you got the same proportional rise (ie 0.14 of the starting tyre pressure, so on track the tyre pressure is 1.3 bar), your tyre temperature would be 52C ;ie 2C hotter.
You can see that you aren't going to make up that 10C that you are missing on track without raising the pressure way above the usual limits or increasing the amount of energy you put into the tyres by driving.....or heating the track.
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TALK about tyres by 'garycooper01' (05 Mar 2009 @ 10:17)
