I recently had BFgs 45 series for like 5 years. Then I swapped them out with FAT fives with a 205-50- size NEW kumho ASTs. PSI set on 32 front and 30 rear.

I like checking my tire pressure every other month. Is it normal for these tires to lose tire pressure every month?

So the fronts were at 32 in August 1st. Today it went down to 30?. Is this normal for this type of tire?

My recent BFgs hardly loss PSI in three months.

 

2 psi difference? Could simply be due to differences in temperature when the pressure was checked.

I wouldn't worry about it unless it continues to do so every month, month after month.

 

TunerN00b is exactly right. Pressure varies depending on the temperature of the tire. This is normally a function of the temperature of the surrounding air, although a tire that has the sun shining on it, or a tire that has been used within the previous hour or two, can also be warmer and have a higher pressure. That's why pressure should be measured with the tires cold (i.e. in the shade and not having been driven) at the approximate temperature in which they will normally be used. The Tire Rack claims that pressure varies by 1 psi for each 10 degrees F difference in temperature, although I have found it to be slightly less than that. It's possible that your previous tires lost air but the pressure measurement didn't drop because you are comparing the lower temperatures of winter or spring with the warmer pressures of summer.

Also, it is normal for tires to lose a small amount of pressure over time, even if the wheels and tires are good. Because I have three sets of tires - summer tires for daily driving, R compound tires for racetrack use, and winter tires for that season - I have tires that sit unused for a portion of the year. I have observed that all of these tires normally lose about 1 psi per month. So this factor alone could also explain the drop in pressure that you are noticing.

Check your pressures regularly, at least once a month, and add air if needed.