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.