Tire Pressure Loss - What's Normal?

[BertL]

I just passed 2 months of S90D ownership with my 19" Cyclone Wheels and Michelin Primacy MXM4 tires, with not 2K on the ODO. I do not rely on TPMS, and check tire pressure monthly with an external gauge, bringing my MS 19" tires back up to 45lbs while cold as my B-pillar tag indicates. What's odd to me is I'm consistently loosing around 3-4 lbs of pressure on all 4 tires each month.

That is excessive compared to Michelin Pilots, Bridgestone Duelers and Potenza I've had on former rides where I'd loose that much pressure in perhaps 3 months or more in the same SoCal garage (and effectively all year around given our more moderate temps) for many years. I don't use Nitrogen. I've tried an alternate pressure gauge with the same readings. I doubt very much I have a stem or installation problem given this is happening on all 4 tires. I recognize different tires have different formulations, so maybe that's all there is to it. I've scanned through the Tire Pressure, Nitrogen, TPMS, etc threads here on TMC, but would appreciate other's experience as I become accustomed to these new tires.​

Is 3-4 lbs tire pressure loss per month just normal for the Michelin Primacy's? Thx in advance.

 

[FlasherZ]

Is 3-4 lbs tire pressure loss per month just normal for the Michelin Primacy's? Thx in advance.

My experience has been to expect about 2 psi per month on my MXM4's. Jerry might yell at me for this, but recently I went about 4 months without checking pressures, and I was down to about 38 from the 45-46 that the service center usually puts in them. Part of that, though, is likely the colder temperature here.

 

[msnow]

Bert - About 1 to 1.5 lbs p/month for me checked on a new digital gauge. How's your measurement compare to the Tesla TPMS dash readout? My TPMS reads a little lower than my gauge for some reason.

 

[AWDtsla]

1lb per 10F drop in temperature. Virtually none otherwise.

Personally I compensate for temperature when I inflate the tires, since this is usually done in a heated garage and the car drives in the cold.

 

[BertL]

Thx for everyone's input. Seems like I'm on the high end of average. Drop in temp may account for one point or so of that, but not a lot more given our daily lows here have been between 57 and 44 since I've taken delivery.

...How's your measurement compare to the Tesla TPMS dash readout? My TPMS reads a little lower than my gauge for some reason.

Just re-measured my pressure, then drove the MS down the street until the TPMS measurements appeared. My TPMS display is well within rounding error of what both my digital gauges displayed before taking off with cold tires in 55F temperature (my digital gauges both go to tenths and reported within 1/10 of one another).

 

[jerry33]

Three to four psi a month seems a lot to me unless there is a temperature drop. Nitrogen won't help this. I'd guess there is something leaking, probably through some damage to the tubeless liner, poor seating so that the bead toe isn't in contact with the wheel, or perhaps even a leak in the wheel itself. Because of the slowness of the leak it's going to be hard to find.

 

[CHG-ON]

I am not sure why, but I am losing no pressure whatsoever over the past 2 months. I am running Hankooks. When first installed, I did lose pressure. Now, not one pound. Perhaps they took some time to seat the bead. Kinda nice.