Tyre pressures on 20" set to over 100mph

Just checked the tyre pressures on my Dynamic and there are two pressures listed, under 100mph or over 100mph this only seems to be for the 20" wheels.

Mine are inflated to the pressures for over 100mph but as I wont be going that fast should I deflate them a bit to the lower pressures or leave them as set from the factory?

Wouldn't normally worry too much but 39psi is quite high and it may improve the ride a little on the lower pressures and prevent the middles wearing out first

If you lower them you might see a decrease in fuel consumption as well, and the ride will be less harsh. Just remember not to go over 100mph on the road!

Could it really save fuel? I imagined it may use slightly more fuel as the lower pressure tyres would have more drag

I realise we're only talking a tiny bit

I believe higher pressure = higher mpg, lower pressure = lower mpg.
Whether you will save enough on the fuel to more than compensate for the price of replacing the tyres a bit more regularly though is anyones guess.
Also need to consider that higher pressure means a smaller contact area with the road and so may well affect handling etc.
Personally I'd stick to the recommended pressure (less than 100mph on british roads) and regularly check them.