Tyre pressure

[dubby99]

Is it important to get your tyre pressure right before anything else as far as chassis setup?

If the tyre pressures are not the same in all 4 corners when hot, will that have an effect on handling

I am currently racing rotax light and the tyre's we are using are the brigestone YGK,so does anybody know what hot pressures to run them at.

[speedy king]

Tyre pressures are vital. You can win or lose a race by them. You tend to need them softer in the cold and harder in the hot weather. When i used Bridgestone YEQ's for Junior Rotax we always started at 15psi for all 4 tyres for first practice and then altered trhem from there. But most the time they stayed around 15psi, 13, 14, 16 etc.

Vital set-up

[Revracing]

Interesting Speedy King, in all the years I was racing Karts we never had harder pressures in warmer weather, the total opposite in fact!

From my experience, the softer the tyre the lower the pressure, (there are limts and compromises of course).

[speedy king]

Well, thats what i thought. But earlier in the summer it was something olike 28 degrees so i put my preasures down like what you said and i thought at the time and they were awful, too grippy, then overheating and understeer. Put them up and -the fact i had more or less destroyed the tyres by this time they were much better.

Like you say though, it may differ with tyre compounds but i too at the time thought they need to be softer for higher temperatures

[#15 tkm 4/]

in my class, we use the maxxis red's and we never ever go above 12psi! i think we run aslow as 4-5psi in the really hot weather and about 12psi in the cold

[speedy king]

4-5!!!!!!!!! Thats incredible! i'd think i'd have a flat tyre at that amount!

Looks like Revracing may be right, it does all vary on different tyres and their compounds

[Alex Hodgkinson]

4-5 psi?! That's mental! the FSA guys I know hardly ever go below 6 psi when they're using Vega XT's (super super soft) in Malaysia!

[Revracing]

If memory serves, we used to run 8psi fronts and 10psi rears on sticky rubber in warm weather, any lower and you needed bead retainers to stop the tyre comming off the rim.

One year I had an outside front tyre roll off the rim whilst negotiating the bend at the end of three sisters straight, needless to say I finished up some distance from the track.......

[Alex Hodgkinson]

^^ Yup that totally makes sense Revracing. In ICA this summer I was using around about those values, give or take a few psi. And less of a front/rear difference, because the chassis in stiff hot weather setup is very sharp on turn in, just as I like it .. any less pressure would be to much, if you get me?

[hgmonaro]

We always ran 1-2 psi higher in the rears and more on colder days (In the wet we'd pump them up heaps). We altered them based on what the tyre looked like. If they went all motterly across the full surface they were working (after a race you pick the kart up off the track and you need to unstick it!) This means the chassis setup is intertwinned with the tyre pressures.

Whatever it takes, you need them working at the 1st corner cause any spots you pick up then are much easier to hang onto than get back spots late in the race.

[Alex Hodgkinson]

The lower down a grid I start, the more pressure I put in all round (sometimes!) I do this because with higher pressures the heat builds up faster, so I can get stuck into passing people sooner. However towards the end of the race you can start to get too much grip and it'll start bouncing.
So, when I start towards the front of a grid I put less pressure in so I can run at a more consistant pace. However sometimes I go for the more pressure tactic, so I can scamper away at the start. It all depends on who's around me really!

[hgmonaro]