Before You Start / Safety
- Always set pressure from cold values.
- Do not use sidewall max pressure as daily operating target.
- Reinstall valve caps after service.
Required Tools
- Reliable pressure gauge (digital preferred)
- Air source (compressor/pump)
- Notepad/phone for FL/FR/RL/RR logging
Label-first rule (critical)
Use this order of authority:
- Driver-door-jamb tire-pressure label (primary)
- Owner manual for your exact tire size/market
- Workshop setup sheet only if it matches (1) or (2)
NBs often run mixed wheel/tire sizes over their lifetime, so one universal internet pressure value is not reliable.
Practical NB pressure context
Mazda owner-manual family references commonly show around 200 kPa / 29 psi front and rear for many stock-size road setups.
Treat this as context only—your door label wins if different.
Step-by-Step Procedure
1) Measure all four tires cold
- Remove valve cap.
- Press gauge squarely on valve stem until hiss stops.
- Record each corner before adjusting.
If gauge angle is poor, readings can be low and inconsistent.
2) Adjust to target pressures
- Add air in short bursts.
- Recheck after each burst.
- If overfilled, bleed briefly and remeasure.
- Keep left/right equal on same axle unless label specifies otherwise.
3) Check spare too
A flat spare is a failed roadside plan.
- Temporary spare: follow spare sidewall target (often high pressure).
- Full-size spare: use same cold target as road tires.
4) If tires are warm (fallback only)
If you cannot wait for true-cold setting, apply a temporary correction and reset later when cold.
Common practical rule: warm reading can be around +4 psi above cold target.
Example:
- target 29 psi cold,
- warm temporary set ~33 psi,
- then reset to true cold target later.
5) Leak triage if one corner keeps dropping
If one tire loses pressure faster than others, inspect:
- tread puncture,
- valve core/stem leak,
- bead/rim corrosion leak,
- wheel crack damage.
Repeated top-ups without diagnosis are not a fix.
Maintenance interval
- Check at least monthly.
- Check before long trips.
- Recheck after large ambient temperature swings.
Rule of thumb: about 1 psi change per ~10°F (6°C) ambient change.
Verification / Post-service checks
- All 4 corners at target when cold
- Valve caps installed
- Car tracks straight with stable steering feel
- No recurring low corner at next weekly check
Sources
- Mazda Owners Manual (MX-5 family tire page) — pressure table context and tire-spec format (includes 200 kPa / 29 psi examples for standard fitments). Retrieved 2026-03-15. https://owners-manual.mazda.com/gen/en/mx-5/mx-5_8gg1ee17j/contents/10020109.html
- Bridgestone — How to Check Tire Pressure with a Tire Pressure Gauge (cold-tire method and maintenance rationale). Retrieved 2026-03-15. https://tires.bridgestone.com/en-us/learn/tire-maintenance/how-to-check-tire-pressure
- MELLENS — Mazda Miata Factory Service Manual archive (year/VIN NB reference source). Retrieved 2026-03-15. https://www.mellens.net/mazda/