Tuga2112 wrote:after reading your comments ill revert back to 30.
Joao,
Don't forget, the OP and Mike (MPx) are running FED & S2 cars - both with 16" wheels...... the tyre (tire) side walls are a different aspect ratio, so the 'stiffness' will be different to an SE/NA.
As with everything, different things suit different needs - for pure 'grip' you will use a different (lower) pressure to getting best economy - as the air expands with heat, the pressures will rise during a trackday session far more than on a 'normal' drive (commute).... and will raise more on a fast motorway run than on a town centre drive.
The whole aim is to get the most 'flat' area of tyre across the whole width of the rubber at all times - but that gives worse economy due to the extra friction - so choose what is best for you. (Economy *may* be a bit of a false thing if the centre of the tyre wears faster than the outer edge, and so they need changing sooner - it all depends on the individual case).
The very best "advice" is to just check that the pressures are the same on each axle, and probably on all 4 corners.
