I’m getting pressure always wrong. On last service it was over inflated. Just now checked it is under.
the ring inflator I have has screw type which is annoying, can’t just put it on easily, threads are already getting damaged on few uses.
There are two settings, high load and low load, occasionally I have high load, do people adjust pressure regularly?
Tyre pressures, are dependent on load on the tyre, manufacturers list pressures in the handbook, for differing loads, and types of roads you will be driving upon. The higher the pressure, the lower the rolling resistance, but the smaller the contact area with the road, so it is always a compromise, so always best consult the book.
Me, I have a big mains compressor, in the garage, and air piped around the garage and workshop, with around 20 tyres to maintain, but I used to have many more. I use a professional inflater, to check them, and a list of the pressures on the garage wall. I only use the car irregularly now, but the pressures are checked and adjusted to the precise pressures, every time I take the car out, before it goes out on the road.
Over-inflated, your grip on the road is less, and the centre of the tread wears more quickly. Under inflated, then your economy suffers, and the tread edge wears quicker. Get it right, and your tyres last longer.