Track Tire Pressures

The number that matters is hot pressure, not cold. The placard figure on your door jamb (32 psi front and rear on most ND trims, set for ride and fuel economy) is a starting point for the street and nothing else. On a hot tire the gas inside expands, so a tire you set to 30 psi cold in the paddock can be sitting at 38–40 psi by the end of a session. You tune to where the tire ends up, then back-calculate the cold pressure that gets you there.

Two things make the ND a special case. It’s light (roughly 2,300–2,400 lb depending on year and trim), so it doesn’t load the tire the way a heavier car does, and the OEM tire is narrow. Base ND ships on 195/50R16; Club and Grand Touring ship on 205/45R17 Bridgestone Potenza S001s. Light car plus narrow tire means you generally run lower pressures than the internet’s generic “track day = 40 psi front” advice, which is calibrated for heavier sports cars.

Why hot pressure is the real target

Pressure rise is heat. A tire builds grip as it warms into its working range; too little pressure and the carcass folds over, rolling onto the sidewall and overheating the shoulders; too much and the center crowns, the contact patch shrinks, and grip and braking suffer. The goal is a contact patch that sits flat under cornering load and a tire that lives in its temperature window.

Because the rise is what you’re chasing, the workflow is always:

Set a cold starting pressure in the paddock.
Run a session (or, for autocross, a run or two).
Measure pressure immediately when you come in, before it bleeds off.
Bleed down to your hot target, or add cold pressure next time if you came in low.
Reset to the same target before every run so each run starts equal.

Autocross compresses all of this. A run is 45–70 seconds, so the tire never reaches the steady state it would on a road course. You set a higher cold pressure so the tire is already near its window on the line, and you reset to the same number between runs because they cool down between cars.

Starting windows by tire type

Treat these as starting points, not gospel. The right number depends on your wheel width, camber, ambient temperature, and how hard you drive. Every honest source says the same thing: start here, then let the tire tell you. All figures are hot unless noted.

Ultra-high-performance street (Potenza S001, Michelin Pilot Sport 4S, etc.)

Stock-ish tires on stock-ish wheels. These have soft sidewalls and don’t love heat, so keep pressure up to support the carcass.

Track (road course): roughly 36–40 psi hot front, a couple psi lower rear. Watch for greasy, overheated tires after a few laps — UHP street tires give up before a 200TW does.
Autocross: mid-to-high 30s, often 36–38 psi, because the run is too short to build much heat and you want sidewall support immediately.

200-treadwear (Bridgestone Potenza RE-71RS, Falken Azenis RT660, Yokohama Advan A052, Goodyear Eagle F1 SuperCar 3R)

The autocross and grassroots-track standard. Stiffer construction than UHP street tires, so they tolerate lower pressures, and lower pressures often find more grip on a light car.

Track: commonly low-to-mid 30s hot. Many ND runners land around 32–35 front, a couple psi lower rear.
Autocross: this is where the ND goes low. With meaningful camber, ND drivers on RE-71RS have reported hot pressures in the high 20s to low 30s — figures like 29 front / 27.5 rear and 33 front / 30 rear show up repeatedly. Wide 225-section tires on 9-inch wheels with serious camber go even lower. Start conservative (mid 30s), then air down a pound or two at a time while watching feel and lap times.

A light car with negative camber needs less pressure than the tire maker’s generic chart suggests, because there’s less weight folding the tire over and the camber is already keeping the patch flat in the corner.

R-compound (Hoosier A7/R7, Yokohama A055, Goodyear RS)

Race rubber with stiff sidewalls. Hoosier publishes guidance for the A7/R7: for autocross, start within 1–2 psi of your hot target and reset between runs; the tire makes peak grip when paddock surface temps read roughly 110–140°F. Hot pressures live lower than 200TW tires (often around 30 psi or below on the ND, sometimes lower in front), but follow Hoosier’s own sheet and your pyrometer rather than a forum number.

The minimum-safe-pressure floor

There’s a hard floor under all of this. The common rule of thumb is to divide total vehicle weight (with fuel and driver) by 100 to get a minimum safe cold pressure. A ~2,750 lb car-plus-driver lands around 27.5 psi minimum cold. Going below the floor risks rolling the tire off the bead under load or chewing up the sidewall. If your tuning is pushing you under it, the answer is more camber, not less air.

Dialing your own window: pyrometer

The pressures above get you in the ballpark. A pyrometer tells you exactly where you are. Use a probe type, not the infrared laser kind — the laser reads only the surface, which cools the instant the tire stops rolling. The probe reads the rubber a few millimeters down, where the real temperature lives.

Coming off track or after a run, work fast and take three readings across each tire’s tread: inner, center, outer. Write them down. Two things to read:

Pressure shows up as the center temperature relative to the shoulders. If the center is hotter than the average of the two edges, the tire is crowning — too much pressure, let some out. If the center is cooler than the edges, the carcass is folding over — too little pressure, add some.
Camber shows up as the inner-to-outer spread. You want the inside edge running somewhat hotter than the outside, with an even gradient between, because the loaded outside tire leans onto its inner shoulder mid-corner. SuperMiata’s guidance is to aim for the inside roughly 20–30°F hotter than the outside with a smooth step across the tread; if the outer edge is much hotter than the inner, you need more negative camber. A spread of 15–20°F across the tread is normal; tighter than that suggests you’re near the most camber you can run without wearing the tire unevenly.

Pressure and camber interact, so change one variable at a time and re-measure. The fastest setup doesn’t always show dead-even temps (peak grip and even wear aren’t always the same point), so cross-check against lap times or run times, not temperatures alone.

Dialing your window: chalk (the cheap method)

No pyrometer? Chalk works. Draw a line of tire chalk (or a paint marker) across the tread from the outer shoulder onto the sidewall. Make a few hard runs, then look at how far the chalk scrubbed off.

Chalk worn off onto the sidewall means the tire is rolling over — pressure too low, or not enough camber.
Chalk still present on the outer shoulder with the center scrubbed clean means you’re riding the center — pressure too high.
Chalk scrubbed to the edge of the tread but not onto the sidewall is roughly where you want it.

Chalk shows you the contact patch under load but tells you nothing about temperature, so it can’t separate a pressure problem from a camber problem. It’s a fine first pass before you own a pyrometer, and a useful sanity check at an autocross where you don’t have time for probe readings between runs.

Practical paddock routine

Buy a quality digital gauge and a pyrometer or chalk; the placard and a guess won’t get you there.
Log cold and hot pressures every session along with ambient temperature — a 90°F day and a 50°F day need different cold settings to hit the same hot target.
Reset to the same hot target before every run so runs start equal and your data means something.
Change one thing at a time. Pressure, then camber, then re-measure.
Mind the minimum safe pressure floor. If you keep wanting less air, add camber instead.

/nd-miata/track-tires/ — choosing 200TW vs R-comp for the ND
/nd-miata/autocross-tires/ — autocross-specific tire picks
/nd-miata/alignment/ — camber and toe settings that drive your temperature spread
/nd-miata/wheel-tire-fitment/ — wheel widths and sizes for the ND
/nd-miata/track-day-prep/ — the rest of the track-day checklist