Work out your tyre pressures

A step-by-step guide to getting a recommended tyre pressure for each corner of your kart using the Apex Tyre Calculator.

The Tyre Calculator lives on the Tyres page in Apex (select Tyres in the sidebar, or in the bottom navigation bar on a phone). It takes your tyre, the weather and the kind of session you're running, and returns a target cold pressure for each tyre plus the hot pressure you're aiming for. You don't need any telemetry, kart or session data to use it.

What you need

• The tyre brand and compound you're running (e.g. Mojo and its medium compound).
• A rough idea of the track temperature in °C, or a track and date so Apex can estimate it.
• Your kart class and the type of session.

Steps

1. In the sidebar, select Tyres.
2. In the Tyre & Wheel card, choose your brand under Tyre Manufacturer.
3. Choose the compound under Tyre Make (this list unlocks once a manufacturer is chosen).
4. In the Track Condition card, set Track Temperature (°C) (any value from −10 to 50, in half-degree steps).
5. Set Weather (for example Dry).
6. Set Grip to match the surface — Green, Low, Medium, High or Very High.
7. Check Direction (Clockwise or Anti-clockwise) — Apex matches it to the track when it knows the layout.
8. In the Session card, set Class and Session Type.
9. Select Calculate Pressure.

What you'll see

A Pressure Readout appears below the button with a 2×2 grid of corners — Outside Front, Inside Front, Outside Rear, Inside Rear. Each shows a nominal cold pressure in PSI with a low–high range, plus a single Target Hot Pressure range to aim for once the tyres are hot.

Tips

• Calculate Pressure stays greyed out until both a Tyre Manufacturer and a Tyre Make are chosen — these are the only required fields.
• If you enter a temperature outside −10 to 50 °C you'll see "Track temperature must be between -10 and 50°C"; correct it and calculate again.
• For a more detailed result that also factors in your wheels, race distance and the track surface, turn on the 6-Step toggle before calculating.
• Add the optional Laps and Driving Style to sharpen the estimate.

Frequently asked questions

Do I need to upload a session or set up a kart first? No. The Tyre Calculator works on its own — just choose a tyre, set the conditions, and calculate.

Why is the "Calculate Pressure" button greyed out? You haven't chosen a tyre yet. Select a Tyre Manufacturer and a Tyre Make; the button then turns on.

Is the recommended pressure the cold or hot pressure? The per-corner figures are the cold pressures to set. The separate Target Hot Pressure is what those tyres should rise to once they're up to temperature on track.

What if I don't know the track temperature? Choose your Track and Setup date in the Tyre Setup card; if forecast data is available, Apex estimates the track temperature for you. Otherwise, type your best estimate into Track Temperature.