Start here for fast, realistic tire pressures. Enter rider and bike weight, tire width, discipline, surface, and setup.

The calculator provides starting-point pressures based on load and tire size. Always validate on your own roads and stay within tire and rim manufacturer limits.

Tire pressure calculator

Enter your weights, tire width, and setup. Results are starting points: adjust on the bike and follow tire/rim limits.

Rider and bike weights use this unit.
Range: 70–400 lb (32–181 kg).
Bike + bottles/tools.
Total system
— lbs
Front load
— lbs
Rear load
— lbs
Guide: 25–35 mm
Most drop-bar bikes sit ~45% front / 55% rear. MTB varies with terrain and position.
Baseline is 68°F / 20°C. Adjusts pressures ~proportional to absolute temperature, clamped to safe floors and caps.

Suggested pressures

Waiting for inputs

Front

—psi Try ±2: —

Rear

—psi Try ±2: —
  • Start here, then fine-tune based on feel, grip, and rim/tire limits.
  • Heavier loads, narrower tires, or tubes often need more psi. Rougher surfaces and wider tires generally need less.
  • Check max/min printed on your tire and your rim maker’s recommendations for your rim width.
Built for quick estimates. Use common sense and manufacturer guidance to avoid damage or injury.
Advanced settings
Road 17–21 mm. Gravel 23–25 mm. MTB 25–30+ mm.
Use effective width from rim: measured ≈ labeled + 0.4 × (rim − 19 mm)
Effective width: — mm
Display only: internal math uses psi.
Model assumptions
Enhanced modeling is always on: stronger rough-surface reductions (≈ −12–20%), rim–tire shape factor, small casing effect, and discipline tilt. Temperature overlay scales pressures with absolute temperature (baseline 20 °C / 68 °F) and clamps to safe floors and discipline caps.
Expert calibration check (Silca / René Herse)
What this does
Compares fixed reference scenarios to tight published bands (Silca / René Herse–like). By default we use a neutral baseline: typical rim widths (road 21 mm, gravel 25 mm, MTB 30 mm) and 20 °C. Toggle below to use your current rim & temperature instead. “Inside” means both wheels fall within the benchmark band.
Scenario Inputs Benchmark (psi) Your result Δ vs range Inside range?
Summary —

Quick guidance

  • Load: heavier rider + bike = more pressure.
  • Tire width: narrow tires need more, wide tires need less.
  • Surface: rougher terrain favors lower pressure.
  • Setup: tubes often require slightly higher pressure than tubeless.
  • Front vs. rear: the rear usually carries more load, so it runs higher.

How this calculator works

This calculator estimates tire pressures by balancing load per wheel against tire width, then applying adjustments for surface, casing, rim width, riding style, and ambient temperature.

Formula: pressure = (wheel load ÷ tire width) × discipline constant × surface adjustments × casing modifiers × temperature scaling, with safety floors and caps applied.

  • Wheel load: derived from rider + bike weight and front/rear distribution.
  • Discipline constants: baseline factors for road, gravel, and mtb.
  • Surface and casing: small percentage modifiers for roughness and tube vs tubeless.
  • Temperature scaling: automatic adjustment using absolute temperature with a 68°F/20°C baseline.
  • Safety floors and caps: guardrails that prevent unrealistic or unsafe outputs.

Advanced features

  • temperature adjustment: automatically scales pressure for riding conditions using absolute temperature (baseline 68°F/20°C).
  • rim–tire interaction: accounts for rim internal width effects on tire shape and effective width. Includes an optional measured-width estimator.
  • expert calibration check: compares results against industry benchmarks inspired by silca and rené herse ranges.
  • pump mode: large number display for trackside use, plus shareable links that open pump mode directly.
  • sharing: one-click links preserve your setup and results for easy reference and comparison.

Measurement tips

  • rider weight: include clothing, shoes, and bottles you usually carry.
  • bike weight: complete bike; close enough is fine.
  • tire width (mm): use labeled or measured inflated width. advanced: enable the measured-width estimator to reflect how rim width changes actual tire size.
  • front weight distribution: typical ranges:
    • road: ~44–46% front / 54–56% rear (calculator uses 45% default)
    • gravel: ~43–45% front / 55–57% rear
    • mtb: ~42–45% front / 55–58% rear

Notes and limitations

  • Results are starting points, not exact values. Fine-tune in small steps.
  • Rim internal width changes actual inflated tire size and safe pressure ranges. Narrow rims at high pressure increase blow-off risk.
  • Very low pressures increase risk of burps (tubeless) and rim strikes.
  • Very high pressures reduce grip and comfort.
  • Temperature matters: pressure rises in heat and drops in cold. Set pressures at the ambient temperature you’ll ride in.
  • Tubeless setups may lose pressure faster over time as sealant permeates. Check often.
  • Plus-size tires (>50 mm) often run below 20 psi, where inserts and casing stiffness play a bigger role than formulas alone.

Safety and disclaimer

This calculator estimates performance-oriented pressures. Always follow the tire and rim manufacturer’s stated limits for your exact size, construction, and rim type (hooked or hookless). If the suggested pressure exceeds any published limit, use the manufacturer’s limit or change components.

Important:

  • Hookless and non-ETRTO setups can be highly sensitive to pressure.
  • Surpassing manufacturer limits may cause tire blow-off, loss of control, equipment damage, or injury.

Built for quick estimates. Use common sense and manufacturer guidance to avoid damage or injury.

Other calculators

FAQs

How accurate is this calculator?
Accurate enough to land in the “fast and safe” range for most riders. Fine-tune on your own routes.

Should I enter labeled or measured tire width?
If you know your inflated width, use it. Otherwise, the labeled width is fine. Advanced users can enable the measured-width estimator to account for rim width.

Does the calculator adjust for temperature?
Yes. It uses absolute temperature scaling with a 68°F/20°C baseline. Set pressures near the temperature you will ride in.

Do tubes need more pressure than tubeless?
Slightly more to reduce pinch risk. The casing adjustment accounts for this.

What if I run inserts?
Inserts can allow slightly lower pressures off-road. Start with the suggestion and reduce carefully while checking for rim strikes or squirm.

How should I set front/rear distribution?
Road bikes are ~45% front / 55% rear. Gravel and MTB are often slightly more rear-biased. Adjust the slider to reflect your bike and position.

Closing summary

Tire pressure should balance speed, comfort, and safety. This calculator gives a solid starting point by factoring in weight, tire size, and riding conditions. Most riders will benefit from fine-tuning ±2 psi for their terrain and setup. Always confirm pressures against tire and rim specifications, and remember that temperature, sealant, rim width, and tire construction all influence the final result.

Sources

  • MDPI Applied Sciences (2020): The effect of bicycle tire pressure on rolling resistance and vibration. DOI: 10.3390/app10093156
  • Journal of Applied Mathematics (2015): Bicycle tire model for steady-state operation. DOI: 10.1155/2015/191075
  • Berto, F. (2006): All About Tire Inflation. Bicycle Quarterly Press. ISBN: 9780976546000
  • Taylor & Francis (1999): Vibration transmissibility of bicycles. DOI: 10.1080/001401399185009
  • PLOS ONE (2024): Cycling performance and tire pressure on variable surfaces. DOI: 10.1371/journal.pone.0302821
  • Taylor & Francis (2013): Effect of tire pressure on cycling performance. DOI: 10.1080/02640414.2013.792945

Reviewed by: Greg Stellato
Last reviewed: September 22, 2025
Last verified: September 22, 2025
© 2025 the manual by FSCC | This article licensed under CC BY-SA 4.0
Cite as: "Bike tire pressure calculator," the manual by FSCC