I posted this
here, but thought I'd share since this thread aligns with my experience.
I've been experimenting with this for my upcoming road trip as well as daily driving and track days.
This is the method I follow:
- Drive car several miles to get tires up to temperature.
- Park vehicle and use a quality digital tire pressure gauge to check pressure. I use a Michelin tire pressure gauge.
- Adjust pressure as needed so that all tires are at equal pressure.
- Drive vehicle a few miles to get tires back up to temperature.
- Compare results with onboard tire pressure monitor.
Ultimately, you would want to balance the tire pressure so that when the vehicle is under load, the tire air pressure remains as equal as possible. For instance, my current set up is the following. This allows room for extreme cases (long road trips, spirited driving, etc.) were the tires are building heat and the air pressure rises to remain under
or at the 51psi max pressure recommended by the Continental Tires.
Right front tire: 47.6psi
Right rear tire: 47.3
Left front tire: 47.9psi
Left rear tire: 47.6
Looking at these values you can see that when my M3 is at load the tire pressure remains pretty equal with the lowest value (right rear) 0.3psi under the average value versus the highest tire pressure (front left) at 0.3psi over the average. The added weight from the driver (myself) accounts for the variance. Some fine tuning might bring these values even closer.
**These examples are based on an F80 M3 with a driver at 5'10, 165lbs. Full tank of gas, and no other cargo. Wheels are 19" with OEM Continental Tires. Your experience may vary.