By checking tire pressure once a month, you'll get a good idea how they are performing. If your tires are fairly new and continue to leak air, you should consult your dealer or mechanic. You may have a faulty valve or other damage that is difficult to detect... which could unfortunately result in the need to replace the tires completely. But with proactive maintenance, you could catch an issue before it becomes a problem, and just end up needing a small repair.
For more suggestions to keep your car running its best, check out our library of Vehicle Maintenance Tips