Tire Inflation Frustration

90% you have two slow leaks

 

Much higher than the chances of the alternatives you are stretching for.

Valves can develop slow leaks too. I've needed to swap out a couple bad valve cores.

 

100% slow leaks in tires or valves or (cracks in) rims.

 

Rotating the tires front to back should provide valuable information.

 

There is no way rotating tires will change the low pressure problem. You should do it anyway to improve tire life.

 

It's a viable trouble shooting technique. If the tires + rims are rotated back to front and then checked a week later, the low pressure will be in the rear if the rires+rims are leaking.

As noted in post #6, it's essential that you make one change at a time when trouble shooting.

 

Soapy water (or maybe even just plain water) should be able to detect leaking valve cores without swapping them. Look for bubbles. If no bubbles come out the stems above the cores, then no need to replace.

In my experience, slow leaks on the tread from not-yet-detected punctures are more common than valve leaks. And bead leaks are at least as common as valve leaks. A tire shop can quickly find any of them with a dunk tank.

 

Good grief! Any tire shop can diagnose and fix leaking tires. Why would anyone "troubleshoot" the problem while accepting accelerated tire wear and putting their family at risk with low pressure tires?

 

A spray bottle of water and a bit of Dawn dish detergent works wonders when sprayed all over a tire. Sometimes the most simple and obvious answer is 'the answer'........you will likely be surprised by the amount of bubbles even a small leak can make.

and no, the TPMS turning on and off is NOT a normal thing, even with temperature variations, especially yours. If cold weather causes pressure to drop, and then you pump it up a bit, pressure will increase during a warm spell, then decrease back to the same value the next time temperature drops to the same point.

 

With respect, ‘22-25psi’ from ‘40psi’ tire pressures are ‘low’.

 

AHEM.
It WILL provide some data to convince you that the problem really IS with the tires/wheels and not their mounting position though.

 

I have a wheel/tire on the driver side of my Prius v 4 that veeerrrrrryyyyy slowly loses pressure. Talking to a very knowledgeable friend he said it was likely, because of the aluminum wheels, a bead/rim leak. i just check that wheel frequently. Right now it's on the front. I have the same problem on my recently acquired low mileage '09 RAV4 Limited. Coincidently that is also on the left front right now.

He said a friend who owns a tire shop uses a special sealer whenever mounting new tires on aluminum wheels because he is of the opinion it saves him a lot of remounts. He also related a trucking company that periodically reworks their aluminum rims because of accelerated wear on the bead area.

 

I had the same problem on my first Subaru. When the tire installer (Costco) couldn't fix it, I took it to a more specialized tire shop, who did something of the sort you mention. Solved.

For most people, the cost of having a good tire shop diagnose and fix this problem is significantly less than the time and frustration of mulling over and debating it here.

 

Sure. That is true of MOST things that are discussed in places like this.
Most of the time. But not always.

 

I was thinking that most things discussed here are more specialized and detailed and time consuming than most mechanics have economic time to adequately discuss with their customers. This issue is not one of those.

 

Of course, if you have the right knowledge, diagnostic skills and tools... not so much.

 

You seem to be assuming that "most mechanics" actually have the ability to properly diagnose those things......which may NOT be a valid assumption.
While this should not be one of THOSE things either, underestimating the power of stupidity can be a big mistake.

I recently took a car to a tire shop to have one tire with a large bulge on the sidewall replaced.
When it came back OUT of the bay, I noticed that they changed out the WRONG tire.