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Clark's Garage944 · 924 · 968 · Turbo

Tyre pressure — calculator & logger

Dial in cold pressures so a hot tyre sits at a stable target on track, per corner, and keep a per-track log. Track mode follows the sprint-race method: target a hot pressure, learn each tyre's build from practice, and set cold = target − build. Street mode keeps it simple. Reference tyre: Yokohama 225/50-15; default hot target 2.0 bar.

New to this? Read Tyre Pressure, Grip & Temperature.

CornerCold (set)Hot (in-lap)BuildSet cold
LF
RF
LR
RR

From physics only — log a session to tune to this track.

Pick a track and tyre, and enter cold + hot, to save a session.

Saved sessions

No saved sessions yet.

How to use it

Set and judge pressures cold

Pressure rises as the tyre heats. Set (or measure) cold, and treat the hot figure as the result. On track the hot pressure is a ceiling: a little over your target and the tyre gets greasy and slippery; well under and it feels vague and rolls onto the sidewall.

Use the build (Δ) as your tuning signal

In practice, note the cold pressure you set and the hot pressure on the in-lap. The difference is the build. To land a 2.0 bar hot tyre, set cold = 2.0 − build. Because the track layout heats corners unevenly (more right-handers cook the left tyres), each corner gets its own cold figure — that's why cold can be as low as 1.3–1.4 bar on a hot day.

Adjust for the weather

If the track is hotter for qualifying or the race than it was in practice, the tyre will build more, so drop the cold pressures a touch (roughly 0.1 bar per 10°); cooler, the other way. The track-temp field does this for you — treat it as a starting point, then confirm with an in-lap reading.

Advanced — read the tread with a pyrometer

Take three temperatures across each tread (outer, middle, inner) right after coming in. Middle much hotter than the edges means over-inflated (drop pressure); edges hotter means under-inflated (add pressure). Inner vs outer tells you about camber — a little hotter inside is the negative camber working, much hotter inside suggests too much, hotter outside means you could add some. Cross-check with the camber/toe guidance when that tool lands.

Log every session

Save each session per track and tyre to build a baseline you can return to — “this track, this weather, these cold pressures.” The log stays on your device. Copy it out to share with the team.

Temperature rules of thumb (~0.1 bar/10°) and pyrometer thresholds are starting points — every tyre, track and day differs. Confirm with your own in-lap readings.