Tire Pressure Dropping Quickly

Has anyone noticed the pressures in their OEM tires (Goodyear Integrity) dropping more quickly than expected?

I set the pressures to spec (F-35/R-33) the day I took delivery. The other day, just 4 weeks later, I had to add what I felt was an abnormal amount of air to each tire. The pressures were approximately:
Left front - 23psi
Right front - 25psi
Left rear - 28psi
Right rear - 28psi

I see no evidence of tread or sidewall damage on any tire, and there doesn't appear to any deformation to the wheels.

I have run Michelins almost exclusively for the past 40 years and have never experienced pressure drops like this. The Michelins normally lost about 10% over 10-12 months, never as much as 30% in one month.

Any information would be appreciated. Thanks, Hank

 

Thanks for the reply....
The air temp was about the same each time, low 70's with humidity in the mid 60%s. The same gauges were used, an analog gauge on the electric pump and a handheld digital gauge, both of which are within a half pound of each other.

 

<div class='quotetop'>QUOTE(jamarimutt\";p=\"53097)</div>

I think you're right. If the same pressure drop occurs in the next four weeks, it's back to the dealership for warranty work. I assume the rim/bead seal is covered if there has been no damage to the rim or tire. Also, if I understand the tire road hazard warranty correctly, it covers punctures, cuts, and other damage to the tire.

I was just curious if anyone else had had bad experiences with Goodyear Integrity tires, since they seem to be one of the poorer grade of tires.

Thanks for all your input, Hank

 

Tony, to answer your questions....I hope.

1 - The difference in tire pressures between hot and cold days depends on how much the temp has swung. 10-20 degrees really won't affect the pressure that much, maybe 1 or 2 psi. But if the temp went from +80 to -20 in 12 hours, then you would see a significant change in pressure, maybe 10 or more psi. Since air temp rarely swings that wildly in a short time, if you check your pressures weekly, you will be compensating for the minor daily changes and the big seasonal changes will be taken care of during the weekly checks.

2 - Tire pressures should be checked only when the tires are cold, i.e. after sitting idle for 8-12 hours. This way the tires will have returned to the same temp as the ambient air. Tires will heat up significantly even after only 3-5 miles of driving, and the pressures will have increased as much as 10 psi just in that short of distance. If the nearest tire gauge is in a service station or quick-stop, then try to drive less than a mile to the nearest one, and drive slowly so as not to heat up the tires too much. Better to buy an inexpensive tire gauge at an auto parts store or Wally-World. Try to get a gauge that measures more than 60 psi, that way you can check the spare also...it takes 60 psi. One more thing...if you measure at home, but the nearest air supply is somewhere else, remember how much each tire was low and add only that amount of air. Ignore what the pressure gauge indicates when you are filling each tire because the tires will have heated up and the pressures increased. When you add only the difference in pressure, than the pressures should measure correctly later when the tires have cooled down.

3 - Lastly, if you are on a trip and check the pressures somewhere on the highway, expect to see pressures at least 10 psi above normal. Do not, repeat DO NOT bleed off any air. The pressures will be back to normal the next morning after cooling overnight at a motel, or (shudder) your In-Laws.

Hope this helps, Hank

 

<div class='quotetop'>QUOTE(TonyPSchaefer\";p=\"54113)</div>

Well I'll be darned. Makes sense, since air has mass. Kind of amusing to visualize air molecules as very small marbles inside of a large ring. Wasn't there a kid's game like that years ago? 8)

 

<div class='quotetop'>QUOTE(DaveinOlyWA\";p=\"54292)</div>

Thanks Dave, I didn't know that. Where do you find information like this? The tire websites I've found list only driving performance data, i.e. tread wear prediction, speed range, wet/dry performance, etc. They don't list heat coefficient, rolling resistance, and similar technical or specification data.

What I said earlier was based on 40 years experience with radial general purpose road tires, predominately Michelin. I've had no experience with low rolling resistance and low heat coefficient tires.