So on the way back from the Rolex 24, which was a great time on Saturday, I checked the tire pressures and the just the passenger side rear tire was 2lbs low. The next day I checked it with my gauge and it was a couple pounds lower so I inspected the tire by rolling it back and forth and I could see nothing such as screws, nails, etc. I put 40 lbs in both rear tires and today I checked them both and both were stlll at 40lbs. So, could it be that the position of the tire is preventing air from a hole from coming out? I guess I could move the car so the tire is rotated 180 degrees and check it tomorrow?

 

 

If the 180 degree rotation doesn't help, do you have a large enough tub to pull the tire and submerge it? I think I recall you getting 5-lug wheels, which makes pulling the tire a lot easier.

 

 

I just had to have one refitted where the leak was at the bead.

When they removed the tire there was a bar code sticker in this area causing the bad seal.

That was a 1st for me.

I just mixed up a solution of car wash soap and water and used a microfiber to wet down the entire surface....... bubble bubble......was very easy to find.

 

If you car is maintaining 40, I doubt you have a leak.

 

Every so often I get a "6lbs" low on the passenger side for both front and back tires. Dealer of course has no clue. So I just reset the TPMS and everything is back to normal.

 

Thanks all, and I will report back when I figure it out. I will rotate the tire 180 and check it tomorrow, just to rule that out. I did tighten the valve stem inner a little so maybe that was it. And I do not have a tub or way to remove the tire but I can try the soapy water method with it on the car.

 

I believe these ultra low profile wheel and time combinations need the pressures checked more often than "normal." At least that's my experience.

 

You checked it with what? The TPMS or a real tire gauge?

The TPMS are different sensors, so who knows if they are all equal. A tire gauge does a better job of showing differences.

I use a Longacre gauge that has 0.1 psi resolution and I believe 0.2 psi accuracy.

 

Do this, and with the tire at the same temperature each time.

If the tire never lost pressure before, then gets a slow leak, I would consider (in this order)

1. Small puncture (with or without foreign object remaining)
2. Loose or faulty valve insert
3. Leaking bead (not likely)
4. Cracked or porous wheel (very not likely)

BTW I have had all of these at one time or another.

 

[QUOTE=IXLR8;15599329]You checked it with what? The TPMS or a real tire gauge?

The TPMS are different sensors, so who knows if they are all equal. A tire gauge does a better job of showing differences.

I use a Longacre gauge that has 0.1 psi resolution and I believe 0.2 psi accuracy.[/QUOTE
Both, as stated in my initial post.

 

I just went over 1k miles so 3. & 4. are not possible, especially since I have not hit potholes, curbs, etc. and it the potential leak was just noticed. I rolled the tire 180 degrees this evening and will check it tomorrow (with my gauge).

 

Bob I know you are in Florida. We were in Naples this past weekend and it was very cool. A weather change will affect your pressures also.

 

Bob,

I read your original post a couple of times and if I'm understanding correctly it was down 4 psi total? Cold weather will impact them, but it typically impact all of them. I would be inclined to think it's a small puncture or hopefully the pin in the valve stem that you already tightened.

Even if it hasn't dropped again when you check it tomorrow, if you can easily remove the wheel I would. It is much easier to find a screw/nail with it off. These tires are like magnets for punctures.