[RedDevil]

Originally Posted by Xusi

But if I rise pressure to 40 PSI (3 Bar) (starting from 2.3 bar) wouldn't it be so high that I would lose a lot of grip?

You would not know unless you test it, right?

There's a corner at a junction coming off the highway where two lanes go right.
I could do that corner on the OEM pressure at about 55 km/h max. Any faster and the car would not hold the inner lane.
When I raised it to 40 PSI i could do that same corner at 59 km/h!

Last winter I had a slow leak in my right rear tire. I almost lost it in a corner, going nowhere near what I thought would be the limit. At work I saw the sides bulge, it was at about 15 PSI.
The tire was plugged.
A few weeks later the same happened. This time the tire looked OK, but it had just 28 PSI or something.
The valve had started to leak; I saw it bubble when I put a wet finger on the stem. Some dirt had got in between the valve seal and its rim. One short tap on the pin and the bubbling ceased.
Aired it up again, low grip problem gone.

Now my tires aren't yours and my car isn't yours, so it may act differently.
You need to test it.
Grip is grip; it has the same benefit on braking distance as on max cornering speed, but the latter is much easier to test without precise instrumentation than the former.
So find a safe corner with enough runoff space and try it with varying tire pressures. Then you'll know - and learn something useful about the behaviour of your car too.

I do recall reading a post from someone who did performance tests on road cars on a track, including a slalom test. He wrote he got best times in the slalom test when the PSI was around 55 or 60, way over max sidewall for most tires.

Now lowering tire pressure is a good idea when you are stuck in sand or snow. But you'd have to go really low for best effect - 10 PSI like - and air right back up again once you get unstuck.

If you are worried about grip in cold conditions do buy winter tires! The difference between winter tires and all season tires in the snow is gigantic, blowing anything you can achieve by meddling with tire pressure completely.
I was cynical about winter tires but gingerly bought a set because my Insight had full summer tires which were acting up in the cold wet.
What an eye opener. Another thing you can only appreciate fully if you try it yourself.