Chinook RV

A word of caution out there, folks. We just escaped a potentially serious blowout of the front tire on the freeway owing to sudden loss of pressure. I had new metal valve stems installed just over four years ago along with a pair of Michelin tires. Naturally I assumed the rigid metal option would be more durable and safer at 65 psi, being common in the trucking industry.

I was fortunate to limp home where inspection showed the rubber grommet seal at the base had failed. The picture shows how the stem became loose and can be tilted easily by finger pressure. I have a monthly routine of checking tire pressures and there was no prior warning like gradual loss of pressure. Perhaps a bubble solution check would have caught the onset before we were out on the highway, but this is impossible for the rears where the stems are recessed inside the rim.

Naturally the tire is trashed from running seriously deflated with multiple sidewall bulges showing cord separation/breakage. Based on this I would recommend a check/replacement of valves, even the rigid metal ones, along with tires at the maximum recommended 6-year life. Cheap insurance!

Glad you're okay.

Sine I have the Tireman stems (similar to Borg), can I ask how yours are constructed/assembled in regards to the O-ring? I put my front ones on myself, but it's been a couple of years.... as I remember it, the O-ring is on the inside of the rim (so inside the tire), and then the metal parts are threaded together with Blue Loctite. Now of course I'm wondering if yours are the same (?)

(Also: A friend had the Tireman stems put on at a Discount Tire and they didn't install them correctly. He went back and made them do it over. It was after that that I decided to do the front ones myself (had the others done by Tireman).)

OK, here’s the scoop from our local heavy equipment / truck tire “expert” on metal valve stems. He confirmed the main advantage of metal is withstanding higher pressures safely compared to rubber stems.

However, the disadvantage is metal expands then contracts significantly with normal operational thermal cycles that loosen the thin exterior lock nut over time. This lock nut holds a metal washer compressing the lip from the inner rubber seal that projects through the rim.

Therefore you are supposed to snug, but not over tighten, the lock nut regularly as part of preventive maintenance. I neglected this so never caught the loose lock nut in time. Now being wiser I’ll have to learn to contort my hand with a wrench inside the duallies to take care of the rears. The “expert” said not to use loctite but gave no compelling reason.

I’m not about to invest in a TPMS like discussed on this board but an IR temperature gage sounds like a good investment. The old fashioned wooden tire knocker never told me anything besides inflated or flat! I’ll know more tomorrow with the failed part in hand and take pictures if useful.

My guess of why Loctite was not recommended is because it prevent the nut to be tighten periodically?

I brought a TPMS, but was not able to install the sensor because I can't get to the outer wheels. I need to put a valve stem on them that will enable me to work with the tires. Right now, I can't even put air into some of them!

Thanks for the additional data. I've never heard of a Tireman stem loosening (and he does recommend, and I did use, Loctite) but that's only my small sample plus a few friends and some forum reading. I'd be interested in why not to use it, just cause I like to know things. My rear stems have been in place since May of 2014 (when I had all six done by Tireman), and the fronts since ~March of 2016 (I got new front rims and to make things easier just bought new front stems, put them on the rims myself, and then brought them in for new tires leaving my original front rims and tires in place until I brought the new ones home in the back of the car).

I can't imagine traveling without an IR thermometer anymore in an RV. I didn't get one at first because they were really expensive; but as soon as I started towing with my previous camper van, and saw I could get one for $30, I hopped on the bandwagon. It's so useful! Bearings/hubs and tires are obvious, but they can also be used to diagnose other temp-related things.

BG

PS: Blue Loctite (not red).

Had my new Cooper Discoverer HT3 front tire (to match the existing set) and metal valve stem put on today by a real olde-tyme pro; you know, from the daring generation who used ether explosions to seat beads on stubborn tractor tires. I digress…. he allowed me in the shop past the manager/clerk security checkpoint for a forensic analysis of the failure.

The valve inner rubber seal was good so indeed the 9/16” (14mm) lock nut had loosened. I did notice the new washer he used under the locknut was flat whereas the failed one was dished with less contact area against the rim. Perhaps this was the weak link as the tech said stem loosening was most unusual in his experience. He also recommended against blue loctite for the simple reason it makes subsequent removal too difficult.

I’ll wander into the Amazon forest later for a suitable pyrometer. The deflated tire was almost too hot to touch as might be expected. Trouble is, living in Arizona the pyrometer might already be off scale at ambient Our guardian angels were sure on active duty yesterday!

I bought this IR thermometer, now on sale for $15, presumably because there's a new model:

Etekcity Lasergrip 774 Non-contact Digital Laser Infrared Thermometer Temperature Gun -58℉~ 716℉ (-50℃ ~ 380℃), Yellow and Black

https://www.amazon.com/dp/B00837ZGRY/re ... Szb1NYCHQF

Have used it more than expected, checking everything from AC to heating elements.

I have this one...
https://www.amazon.com/DEWALT-DCT414S1- ... B0043XX8A4

A bit spendy but I have a full array of Dewalt 12v tools to go with it. It was more used prior to retirement while renovating homes. Works great.

If I have one of these thermo gun, how do I use it to check the tires? Just compare the temperature readings?

Just ordered the discontinued Etekcity Lasergrip 774 with the attractive 50% discount. My plan is to use this at fuel stops along the road to scan tires and hubs to detect any “hot spot” indicating trouble.

A really accurate temperature is not essential as temperature is no substitute for a pressure check first thing before starting out while the tires are cool. The idea is to catch any outlier after establishing a baseline set of readings. Not sure how to scan the inner rear tires yet without crawling underneath to aim at the critical sidewall area.

The concept should be a quick and simple check and not get dirty in an oil slick at some truck stop.