Tire Pressure Change Assistant
Work out how tire pressure changes with temperature or altitude so you can adjust your PSI correctly, free in your browser.
Your tyres
Assistant
- Start from your placard: 220 kPa (32 psi). The placard is the safe reference for the vehicle.
- Direction: the new tyre is larger and holds more air, so for the same load it often needs a similar or slightly lower pressure — but always start at the placard and adjust carefully.
- Checklist: confirm the vehicle placard; never exceed the tyre’s max sidewall pressure; set pressures cold; allow for load and towing; recheck after a temperature change; and have a tyre professional confirm the correct pressure for your exact tyre and vehicle.
Educational assistant — not a recommendation
Tyre pressure is safety-critical. This tool is an educational checklist and does not provide a manufacturer pressure recommendation. It uses no built-in load/inflation tables. Always follow the vehicle placard, the tyre manufacturer’s data and professional advice.
Before you rely on this: Safety-critical: treat this as a preliminary check only. Always verify against the governing standards and have a competent person review the result before use.
How to use this calculator
- Enter your placard pressure, and your OEM and new tyre sizes.
- Optionally add the load capacity (kg) of each tyre for a rough direction.
- Read the assistant's guidance and checklist — then confirm with the placard and a tyre professional.
How it works
This is an educational assistant, not a calculator that outputs a recommended pressure. It starts from your vehicle placard (the safe reference) and gives a direction based on how the tyre size and any load capacities change.
It deliberately includes no built-in load/inflation tables. If you enter both tyres' load capacities it shows a very rough proportional estimate only, because tyre load capacity scales roughly with pressure — but that is a crude guide, never a recommendation.
Worked example
Bigger tyre, same load. A larger tyre holds more air, so for the same load it often needs a similar or slightly lower pressure — but you start at the placard and adjust carefully, never exceeding the tyre's max sidewall pressure.
Frequently asked questions
Will this tell me exactly what pressure to run?
No. Tyre pressure is safety-critical and depends on your exact tyre, vehicle, load and conditions. This tool only helps you think it through — always follow the placard and a tyre professional.
Why don't you include a load/inflation table?
Those tables are manufacturer/standard specific and must come from a verified source. To avoid giving wrong numbers, this tool uses no built-in tables; any rough figure comes from load capacities you enter.
What is the placard pressure?
The pressure on the vehicle's tyre placard (usually in the door jamb or fuel flap) for the standard tyre. It's the safe starting reference for your vehicle.
Related tools
- Tire Size Calculator
- Tire Size Comparison Visualizer
- 4WD Tyre Clearance Change Calculator
- Effective Gear Ratio Calculator
- Speedometer Error Calculator
- Alternate Tire Size Finder
Explore more in Automotive, 4WD, Towing & EV.
Cite this tool
Zerdly. (2026). Tire Pressure Change Assistant. Retrieved from https://www.zerdly.com/tools/tire-pressure-change-assistant/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.