Tire Pressure and Temperature: The Rule That Works Summer and Winter

It's one of the most frequent sources of confusion: "my pressure changed by itself." Yes, and it's normal. Understanding why prevents two opposite mistakes — riding underinflated in winter, or deflating a hot tire in summer.

The basic rule

Air in a tire expands with heat. In practice:

A tire set to 2.5 bar (≈36 psi) on a winter morning at 5 °C (41 °F) might only read 2.3 bar (≈33 psi) because it was inflated in summer at 25 °C (77 °F). Conversely, a tire inflated in the morning and checked in the afternoon under the sun will seem "over-inflated."

Two mistakes to never make

1. Never deflate a hot tire. It reads high because it's hot; once it cools, you end up under-inflated — more wear, less grip, risk of overheating.
2. Don't forget to re-inflate in winter. Cold lowers pressure; a tire set in autumn can be noticeably under-inflated in the depths of winter.

The correct method

• Always adjust when cold — that is, before riding (or after at least 2–3 hours parked) — to the manufacturer's values.
• Check more often at seasonal changes, where temperature swings are greatest.
• Never correct a hot-tire reading: if you must check after riding, mentally account for the warmup margin rather than deflating.

This rule applies to motorcycles, bikes, scooters, and even trailers or tractors: anywhere there's air in a tire.

Summary

Pressure follows temperature: approximately 0.1 bar per 10 °C (≈1.5 psi per 18 °F). Set it when cold, re-inflate as winter arrives, and never deflate a hot tire.

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Looking for the exact tire pressure recommended for your bike or motorcycle? On L'Atelier, find manufacturer specifications and ask your maintenance questions.