Obviously, tyre pressure plays a very important part, but there are clearly limits on both sides of the tyre pressure equation. At the higher end, there is the maximum tyre pressure that can be sustained before there is damage to the carcass. At the low end, you don’t want the sidewall almost collapsing, generating massive heat, and have the tyre slipping on the rim. So, you can play around with tyre pressures to optimise your set-up, but there are limitations.
A simple way to find out approximately what pressure is optimal for your combination is to draw a chalkline across the width of the tyre, drive for a bit, and look at the wear pattern of the chalkmark. Wearing more quickly in the centre indicates pressure that is too high, and wear on the edges indicates too low a pressure.
One issue to consider is that, for wet weather driving, despite what you may have heard, it is better to increase your tyre pressure, not reduce it. The reason is that there is a relationship between tyre pressure and the speed at which there is the onset of aquaplaning. In the Imperial system, the equation is 9 times the square root of the tyre pressure. So, if your tyres are at 25 psi, if you drive into a puddle that is deeper than your tread depth, you will aquaplane at 45 mph (72 km/h), whereas if your tyre pressure was 36psi, you would aquaplane at 54 mph (87 km/h). The advantages are obvious.
As far as tyre profile is concerned, the main benefit is one of handling – the lower sidewalls give reduced sidewall deformation under lateral loading, which results in improved steering response and a more stable contact patch
