My 2018 Hyundai Sonata Limited has many neat features, one of which is a digital tire pressure monitor that displays the pressure in all four tires simultaneously.

When I first got the car, with only four miles on the odometer, tire pressures dropped at least 1 psi/week. But now, after several months, pressure drops no more than 1/3rd psi/week. I’m guessing that the tire bead is seating in to the wheels better as miles go by. The tire brand is Continental.

BTW – I have a Milton S-921 tire pressure gauge, recommended by member henryaz. The Sonata’s TPM agrees exactly with the Milton. A nice little gauge at a reasonable price.

It could also be due to the time of the year. Going into the winter season it's not surprising to have to add air in the tires...

Of course in San Diego that may not be an issue!!

quote:

Originally posted by Pipe Smoker:

I’m guessing that the tire bead is seating in to the wheels better as miles go by.

I've never heard of that.

I've never heard of that either. If your tire leaks, it goes flat. The bead is either sealed or not.

My TPMS shows a daily difference of 1 or 2 pounds in all 4 tires.
I chalk it up to ambient temperature cause the pressure to vary.

They were probably originally filled with plain old air. Some of the elements have leached out through the tires to where you mostly have them filled now with Nitrogen.

This is also my theory for why I should never pay for Nitrogen.

The only time I've noticed a change in pressure is either a distinct +/- change in temperature or a leak. I don't use nitrogen which I regard as one of the biggest scams in the automotive world.

I always use a 78% Nitrogen mix when filling my tires...

quote:

Originally posted by bobtheelf:
I always use a 78% Nitrogen mix when filling my tires...

Chuckle.

quote:

Originally posted by bobtheelf:
I always use a 78% Nitrogen mix when filling my tires...

I see what you did there.

quote:

Originally posted by YooperSigs:
My TPMS shows a daily difference of 1 or 2 pounds in all 4 tires.
I chalk it up to ambient temperature cause the pressure to vary.

The TPM of my Sonata reports exactly the same values (1 psi resolution) from one day to the next. Except that after a week or so the values will be consistently less by 1 psi.

I always take the reading immediately after the TPM activates (takes about 1/4 mile of driving) after the car has sat unused overnight in the garage below my condo. As I continue to drive the values go up, of course, as the tires warm from flexing, but I ignore those warm-tire values.

quote:

Originally posted by Balzé Halzé:

quote:

Originally posted by Pipe Smoker:

I’m guessing that the tire bead is seating in to the wheels better as miles go by.

I've never heard of that.

An idea why you (and probably most folks) haven’t seen that high new tire leakage rate I described just occurred to me. My annual mileage is about 3,300, much less than average.

An average driver would put on enough miles for the bead-to-wheel sealing effect that I postulated to be effective before there was significant tire pressure loss.

Wish that I’d thought of that before I initiated this thread.