Bourth (X) May 20, 2011:

Indeed, Ronald, this is a purely 'academic' discussion.

Ronald van Riet May 20, 2011:

In principle you're absolutely right,but the matter of the fact is that this is standard terminology, also used by Michelin itself in all its publications, so one should use it here as well.

Bourth (X) May 20, 2011:

For domestic use I think "cold" means "at ambient temperature, before you've driven anywhere". It's the flexing and friction of tyres when the car is moving that causes the temperature increase they are talking about, an increase that will be greater than even the winter-summer difference in temperate climes.

chris collister May 20, 2011:

Tyres are generally checked cold, but it's all a bit vague at the "domestic" level. How cold is cold? -20°, or +20°? Pressure increases by 1/273 for every 1° rise in temperature, so the stated figures make sense for a 30° rise in a tyre initially at 3 bar. As you can imagine, racing cars are MUCH more precisely controlled.