JOINRims dictate tyre behaviour. It depends on rim material, profile and casting – all suited better for different conditions.
The rim controls more of the pressure curve than the tyre itself.
Here’s how rims affect tyre behaviour and when these changes matter.
The real system: heat in vs heat out
In karting, heat is everything.
- The tyre generates heat quickly through load and flex
- The rim removes heat slowly through material and mass
That imbalance shapes how pressure builds during a session.
If heat enters the tyre faster than it leaves through the rim, pressure rises aggressively. If the rim pulls heat away efficiently, the pressure curve becomes slower and more controlled.
This is why pressure behaviour is not just a tyre problem — it is a system interaction.
Why rims behave differently
Rim differences come down to a few key factors:
- material (magnesium vs aluminium)
- mass
- heat conductivity
- internal air volume
These directly affect heat transfer.
Faster-cooling or lighter rims delay peak pressure and improve stability. Slower-cooling or heavier rims reach peak earlier and increase overshoot risk.
The result is not just “more or less grip” — it is a shift in when and how the tyre works.
Why pressures stop working during the day
A common issue:
Morning: kart feels perfect.
Afternoon: kart feels stuck or hard to drive.
The pressure curve changes due to temperature. So should the pressures — and if that is not enough, then rims.
Rims do not directly create grip. They define:
- when the tyre reaches peak pressure
- how long it stays there
- how aggressively it drops off
So changing rims is effectively changing the pressure curve timing. That is directly related to the heat in vs heat out system.
Rims are complicated.
We made them simple!
Tyre Pressure Tool 2.0 models rim cooling and heat transfer by analysing 6 key principles: material, rigidity, casting, offset, cooling and air volume. Many rims are built into the system.
Launch Tool →Built on thermal behaviour, not guesswork.
Why simple adjustments don’t work
Typical approach:
change rim → adjust pressure slightly
This assumes a linear effect.
In reality, rims reshape the full pressure curve, not just the peak value. That includes rate of pressure rise, peak timing and overheating behaviour.
Small pressure changes cannot fully compensate for these shifts.
How to model it
Tyre Pressure Tool 2.0 treats rims as a core variable.
When rim type changes, the model adjusts:
- heat transfer rate
- pressure build profile
- session behaviour
This ensures pressure recommendations match the actual thermal behaviour of the system, not an average estimate.
Conclusion
Rims do not just “feel different.” They control how tyre pressure develops over time.
They define how quickly pressure rises, when the tyre peaks and how stable it remains.
Understanding this removes inconsistency — and turns pressure from guesswork into a controlled variable.
