just had some new rears fitted on my mk indy

ive got toyo r888 195/55/15

what psi are people running them at for road use?

I'm running 17psi fronts & rears.

Very vehicle dependent but I run mine at 18 psi.

185/60/14 with a vehicle weight of 565 kg.

Generally seems to be somewhere between 16-18psi for our cars.
I'm running 16ish on my 500kg striker with 13"

I run mine at 18psi on 13" wheels

16psi on my striker

16psi here otherwise they don't heat up properly