Hey guys,

I'm new to the RX forum, as I typically hang out in the LS forum keeping my 2007 LS460L in top shape. My wife has a 2016 RX450h and I'm on a mission to understand a tire pressure problem better.

Problem: Simply put, the Right Rear Passenger Tire loses 5-6lbs of pressure every 2-3 days. (Verified with 2 separate tire gauges)

Assessments: Had our Lexus dealer check, two local tire companies, and NONE have found a problem.

Vehicle is under warranty and our Lexus dealer is 1.5hrs away, so we have to schedule our trips accordingly. Taking it back over on appt Thursday, with an expectation that this will be fixed.

Some more background: We had the SAME problem with a 2010 IS350 and my 2007 Lexus LS460. I got sick of it and went to after market rims on the LS (NO MORE PROBLEMS), and we traded the IS (had the air bag issue and wanted us to park it for 10mths...uh NO!) for the RX...and I be Damn if we don't have the same problem on the RX.

Questions:
1) Are the Lexus wheels & tire combo just crap and need to be changed out?
2) Is this more common than I suspect (survey appreciated) and we should be voicing our concern to Lexus corporate?
3) Is there anything in particular that I should ask of the dealer? Road force balance, bent wheel run-out check, what?
or
4) Am I just plagued by a freaky coincidence and just chalk it up to the universe working against me?

I'm an arm chair grease monkey and done some medium to semi-advanced work on my LS (suspension arms replacement, brakes/calipers, lighting, wiring, etc...) and even been getting comfortable using Techstream. So I'm not a complete noob.

Anyway, appreciate any REAL feedback, as this is years of frustration and me constantly putting air into a single tire and making sure my wife checks pressure on trips away, and really something I would think to be SIMPLE to diagnose.

Thanks guys...

 

That sounds like something with the valve. But I have heard of this type of thing happening when the rim flakes off into the tire causing a slow leak. Considering you switched rims and it went away makes me think it’s the rims. Did you use the same valve or a new one?

 

The rims replacement were on my LS460. I can't remember on the valve stems. As for the RX, I've not heard of "rim flakes", so will definitely have them check. Thanks

 

Have you sprayed the tire with soapy water to see exactly where the leak is coming from? Ive never had this issue in any of the Lexi that I’ve owned- I’d say it’s most likely coincidence. Or garage goblins

 

No issues with our RX rims or tires.

 

I had to get a wheel on my old Lexus LS 430 re-chromed because of a leak around the rim. But the car and its wheels were ten years old at the time.

 

Most common issues I see is corrosion on along the bead where the tire meets the rim. Lots of bead seals at my dealer. Other most common one would be a leaking TPMS fitment kit which is the rubber seal at the base of the TPMS sensor (occasionally the sensor it self gets some corrosion along the threads, I just clean it up) the washer and the nut that goes over top. Replacing those is pretty trivial. The only other thing I've seen is a bent wheel where the air was leaking out (but that would be fairly obvious) and also a cracked wheel where the air was leaking out.

 

I would take it back to the most trusted local tire guy (better than a 1 1/2 hour drive) and have them dismount the tire, inspect and clean the rim, inspect and clean the tire bead, inspect and clean the tpms unit, and remount. Cost you a few bucks, but probably cheaper than the drive.

 

I have had 0 issues with my 2016RX loosing tire pressure. I'm running the 20" wheels and have about 50k miles. Sorry to hear about that, I can imagine that would be very frustrating.

 

spray the bead, valve area including the core, jack it up so you can rotate the wheel, or pull it off. also spray the tread area, and watch for bubbling. leaking that bad shouldn't be that hard to find the location.
sounds like you have done mechanical work, this is looking for bubbles, not that hard.

i would bring it to a local tire shop, saves 3 hrs driving, and seems the 3 hrs hasn't been productive so far

i spun wrenches professionally for 25 years, some are a bit tougher to find, but thats a big consistent leak,
my rx has been pressure issue free

 

Yep, pump up pressure so the bubbles are easier to see and spray with soapy water. Shouldn't be too hard to find imo.

 

All good advice and thanks for the commentary. I agree that this should be really simple to diagnose, but most of these (save the TPMS fitment idea) have been done with no joy. I've been out of town, but plan to do the soapy bubbles again myself this evening after work. I believe the two separate tire shops I went to, so maybe it's something that occurs more when driving. I don't know. More to come...

 

Just a quick question. Have you dismounted the tire, checked the rim and tire bead, and carefully cleaned the bead area on the rim? Always worked for me.

 

Good point since the unmounted wheel/tire may not reveal soap bubbles but possibly when driving each time the tire deforms when it touches the road a small transient leak may occur near a dirty or imperfect bead area with each rotation.

 

I had slow tire pressure leak on 2 of my cars (1 is a Lexus ES), and both cars were successfully fixed by the dealers. The tire was loosing ~6->8lbs of pressure per month. It sounds like your leak was faster. The right shop should be able to identified the location. Good luck