RacyLacy16

2016 Lexus RC 350 what should the tire pressure read in the winter

gompka

iTrader: (6)

The sticker on your door should tell you the recommended tire pressure for when your car has been sitting for a while, it doesn't matter if its winter or summer the same cold tire pressure applies.

scooky

Totally correct.
But can also be a little confusing and may require a little more understanding.

TLDR: I target my cold tire pressure to (I think it was 36 in the door jam) when the tires were cold and the ambient temperature is roughly 40 degrees.

This may also be over-thinking it a bit. Having a live per/tire pressure reading in the dash makes it fun to watch what is happening in various conditions.

I recently had my winter tires put on. They set cold tire pressure in the shop. Next morning, my tire pressure sensors went off. Wha??? They actually get this quite a bit.
The day they swapped tires happened to be a hot day for this time of year. 70's. Plus I think they do it in the shop where it is warmer that outside. Totally legit cold tire pressures, but not really what I needed.
We had a clear night so temps dropped hard overnight. Woke up to 30's. That's about a 3-4 psi change for my setup. Therefore low pressure sensors went off.
So cold tire pressure is relative to the environment. Both at the time of measure, but also the conditions you plan to be in.
This is maybe over thinking it, but in my case is relevant to having my TPMS go off for myself/spouse/kids and get an emergency phone call when it happens. So it's worth at least a little awareness/planning.

I decided to add a little air, as I expect my normal conditions for the car for the next 6 months will average in the 30-40's.
It was also warm at that time I was filling, so I set them 2psi high so they would have the cold pressure I wanted at normal conditions for the coming season. I kept an eye on it using the dash readout for a few days and confirmed they were doing what I wanted.

Any amount of driving heats those tires pretty fast and if you have in dash per tire readings you can watch the tire pressure rise relatively quickly. Easily goes up by 4psi on a moderate trip. This is totally normal and expected. I bring it up as that's why they recommend cold tire pressure, there's a significant difference. Also takes quite a while for tires to cool down, so you can't just do it when you get home or to the gas station. I don't remember the time duration. Lots of people drive a few miles to the closes gas station to fill up tires. That's enough to put the tires 2psi higher than cold. Probably within the margin of error, but again if you that on a warm day with warm-ish tires, you might get the TPMS light the next cold morning. (Combination of slightly warm tires with slightly warm day as opposed to cold tires cold morning).

I don't drive with these tires in the summer, but if I did, I might need to let a little air out come late spring. My cold tires at 40degree morning may be correct this season, but could start 3psi over on a 70degree summer morning. Within margin of error? Probably. Just being accurate. In my case, summer tires go on and I'm adjusting them regardless.

fwiw: I didn't worry much about any of this until my recent car. the TMPS readings in the dash caught my attention and helped me wake up to the whole thing. Likely paying too much attention now.