The only reason I know – or I think I know – there’s a difference is because the read-out on the dashboard tells me. It distracts me; and I can’t even be sure it’s correct. The air was put into each tyre with the same device, and inflated according to that device to the exact same pressure, yet the read-out tells me the pressures vary. I rang the dealer’s service centre to have a chat about this. I suspect that when they see my number come up on the screen of their phone system they scatter to all points of the workshop and the person left closest to the phone has to answer it.
This time it was Dom’s turn, and he was relatively patient as he explained to me that these sensors a have a range of accuracy and it’s not unusual for them to return different results to a central processing unit, which is under the floor of the boot. To which I inquired, if they’re known to produce incorrect results, why bother with them? I know tyres are important and yet I get grumpy at the expense when they wear out and need to be replaced. I know that looking after them – not over-inflating them and not under-inflating them – is the way to maximize their life; but I never really know what pressure to put in.
I always get this particular car back from the dealer with what I think are ridiculous pressures: 45 psi in the front, 40 psi in the rear, last time, when the placard on the door frame suggests 40/38 front/rear, respectively. Really, I think someone, somewhere, is guessing at this stuff. And the built-in display is not helping me work out who that is. Perhaps the best course of action is to ignore it. After all, they say that on commercial airliners, nine times out of 10 when a warning light comes on it’s a faulty light.