powersurge wrote:The TPMS goes on when ONE of them goes below a certain point. That ALERTS YOU that a tire is below pressure, and you should check ALL of them.
That is just because Nissan implemented a dummy-light on the dashboard. The car knows
which of 4 sensors is reporting the low pressure -- in fact, the car knows what the exact tire pressures are. The car just doesn't tell you that because someone decided it's sufficient to just provide a the equivalent of a check engine light ("something is wrong; check everything and see what it is").
A better car interface would show you the four tires and the pressures. Leaf Spy Pro does that - and it's an advantage. Tesla does that on the dash.
I agree the car should show you the actual pressure values. Let me relate two experiences which demonstrate why:
1. I was driving my 3/4 ton truck, towing a travel trailer to our campsite. While crossing the Astoria-Megler bridge, I got a low pressure warning. This bridge is over 4 miles long, one lane each direction, with no shoulder. https://en.wikipedia.org/wiki/Astoria%E2%80%93Megler_Bridge
The point being that if you need to stop and change a tire on this bridge, you will cause a massive traffic jam and probably get a visit from the police. Luckily, the truck showed me all the tire pressures on the display, and I was able to see that I still had safe pressure. I made it across the bridge, and while keeping a close eye on the pressure, drove another 10 miles to my campsite, where I changed the tire safely.
2. We also own a Honda CR/V. While driving Hwy 58 in Oregon at about 4 in the morning, I got a low pressure warning in the middle of nowhere. It was cold and dark, and not safe to pull over. Unfortunately the vehicle does not show the actual pressures, so I had to decide whether to pull over somewhere dangerous, or wait until I hit the next tiny town. The car seemed to handle fine, so I sweated it out and kept going about 15 miles into town. When I got out and measured all the tires, they were all fine, though there was a spread of about 4psi between them. Apparently this was enough to set off the alert. Had I been able to read the pressures while driving, I wouldn't have stopped or worried about it until it was convenient, later in the day. (Equalizing all the pressures and resetting the system is all that was required).