by James Wonder
Hello again and I hope you all enjoyed the test day yesterday.
The turnout was really fantastic for a test day!
Okay, before I start I must put a disclaimer on this "tech talk", and
the fact is I am not an expert on Kart tires and tuning, but I will speak about
what I know and try to make parallels to race-cars whenever possible.
Tire compounds:
A tire compound is a combination of rubber type and chemicals used in the
production of the rubber and the tire.
Tire compounds and tire construction are both complicated sciences that
engineers spend their whole lives trying to get right. Compounds alone are
super complex, and change between runs of tires. Race car tires are hand made
and feature very tight tolerances for compound and construction. Even with this
there are variances and tires are not equal.
Our tires are Bridgestone YHC tires and they are very consistent for at least
the first 4 or 5 heat cycles of their life. After that they become harder and
less consistent. Most national teams use them for 4 or 5 heat cycles then throw
them out. A heat cycle can be minimized by keeping the tire in the sun during
hot days, hence making a single day a really long heat cycle. In race cars we
put tire warmers on the tires during practice to minimize the heat cycles, and
for consistency. For the race we do it for best grip right out of the pits.
There is not much you can do for the tire due to the rules and tire prep is
illegal to run at any LIKA event.
I think one note is that soft to the touch is not always a tire with more
"stick".
Tire temperature:
Optimum tire temperature differs for each manufacturer and compound that is
being used. For racing tires it is typically between 180 and 210, but I do not
know what it is for the Bridgestone YHC tires. If someone knows, please let me
know!
Tire pressure:
Tire pressure is one of the things that you can change very easily and is a
very effective tool in tuning the kart. On cold days or for more grip raise the pressure, and for warm days and less grip
lower the pressure. Only change it .5 or 1 PSI and test with the setting. Work
slowly into the pressure setting.
There is a really good writeup on tires at this link and I don't think I can
say it any better than they did.
Other resources:
Because this is a very talked about topic I have included some online resources
for information on kart tire technology:
Russell Karting writeup on Dunlop tires, but still useful.
Some general information is at
this link.