Procedure For Setting Racing Car Tyre Pressures
If you get the procedure for setting your racing car tyre pressures wrong it can mean any work you have done in determining your ideal on track tyre pressures is wasted.
Correct Tyre Pressures
If have not seen it, I wrote this article on how to set your tyre pressures right every time so perhaps have a scan if you are not familiar with the challenge (it has a handy calculator too.)
In summary, you can only set tyre pressures when they are notionally cold and you are in the pits. On the track, the tyres warm up and the pressure goes up.
For best performance, the hot pressures are what matters. The article shows you a method for setting cold tyre pressures so that you can reliably control what the hot pressures will be on track, and, therefore, better control your performance.
It is quite a bit of work to do properly. You, therefore, do not want to waste that effort by not actually setting the cold tyre pressures to the values you intended.
So, assuming your tyres are already nicely mounted on rims and using your suitably calibrated digital tyre pressure gauge, here is a …
6 Step Procedure For Setting Racing Car Tyre Pressures
The approach simply involves adding pressure to the tyres, to a little over your cold target, and then slowly bleeding the tyre down to your cold target pressures.
It goes like this:
- Pressure to cold target +2 psi
- Bleed a bit
- Wait (Count to 5)
- Bleed a bit
- Wait (Count to 5)
- Final bleed to cold target
Why bother? What is going on?
It is worth considering what is going on within the tyre.
Whatever inert gas (air/dry air/nitrogen) you are using to inflate your tyre, I believe this gas can actually slosh about a bit. A bit like water in a bucket.
You want to make sure when you are taking your pressure readings, they are from a stabilised pressure – not a sloshing one.
If you don’t do this you can read the tyre pressure twice (without bleeding) and get a difference – sometimes I’ve seen a 1 psi difference (and the second time it was higher!)
By doing this in three small steps you are minimising the sloshing and increasing your accuracy.
You are also following a repeatably timed process, such that even if there is still a bit of internal gas movement, it is likely to be consistent each time you do this.
Regardless of your thoughts on the sloshing analogy, what you are aiming to achieve is a robust method to consistently set your tyre pressures.
This process gives you that.
Do This And Always Start From A Known Baseline
If the pressures are set reliably, you are starting from a known baseline each time.
You can then more robustly start to determine your hot pressures using mine or your own approach to that.
Yes it is a detailed (arguably OCD style) approach to adopt. But it is easy.
With tyre pressures being so critical, this a simple procedure will ensure you are always setting your tyre pressures as accurately as possible.
Enjoyed this? Check out these other articles:
Want to take the guesswork out of setting your tyre pressures? Try this article including a free calculator: https://www.yourdatadriven.com/how-to-set-your-racing-car-tyre-pressures-perfectly-every-time/
Wondering what the tyres are actually doing? This article should help your visualisation:https://www.yourdatadriven.com/tyre-slip-angle-explained/