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TPMS and valve stem clearance
I am considering getting a TPMS, but have some concerns about getting the sensors installed. Some of the valve steams already have very little clearance. For example, the outer drive wheels have the valve stem pointing inward trough one of the holes in the wheel, but it is offset a bit in that hole. I assume it is offset so you can get a tire inflator on it. Are any of you having to adjust the valve stem position to get the TPMS sensors installed?
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8 Replies
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Yes….I had my stems adjusted.
It’s a personal decision…..I’ll answer for me. Many opinions here i’m sure. You have to be somewhat aware of what inflator you plan to use. Mine is a flexible screw on hose (not the standard truck stop inflator) so this set-up works well for me.
Starting at the steers and tags…..Pressure Pro TPMS sensors will typically fit. At least mine did. Depending on your configuration, they will nest down in the holes of the wheels, but will fit. I didn’t like how recessed they were, so while having some tire work done, I had my stems changed to add about an inch to the length of the stem. I didn’t want them too long as they are a snag hazard and possible more force on them as they rotate at speed. Anyway, my set-up works great so far. You must use Alcoa stems if you change them out. I used Alcoa TR543 straight. The bottom of the TPMS sensor is just at the starting of the hole in the wheel.
For the inner drives…..I use the standard OEM stems for the inners pointed out through one of the holes in the outer wheel. I chose to not run extensions. Tried that and had problems. I use a PVC tool (basically PVC pipe with an open coupler on the end that holds the TPMS sensor) to install the TPMS sensor. Easy Peasy. I do use an extension when I air up, but could use a straight on inflator if you want.
For the outer drives…..I use Alcoa TR544 stems that are factory bent 60 degrees. I wanted to use straight stems, but the design of the Alcoa wheel doesn’t allow for that. They are pointed away from the hub/inner wheel so I can get to them with an inflator. Not sure why you would ever want them pointed into the wheel.
This is the set-up that has served me well. Again, this is what I choose. May not be the best for you.
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I use this inflator (and super happy with the way it works!): https://www.amazon.com/gp/product/B07ZHMB9BF
FWIW, I have no idea why the outer drive wheel stems are pointing inward, except maybe because they would still be accessible if the wheel was flipped for use as inner drive wheel, steer, or tag wheel. I suppose if the stem was not positioned as it is, it would not be accessible when flipped.
Honestly, all of these issues make me wish we had a factory style TPMS with sensors mounted inside the wheels.
Perhaps I can get sensors installed on the steer wheels now and wait for the rear wheel until I change those tires. Maybe I’ll just order the kit for 6 sensors (steer plus toad) for now.
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FYI…..I’ve had the type that are mounted internal to the tire and I prefer the external mounted type. Batteries go bad on the internal type and lots of expense just to change a battery.
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL -
I would like a TPM System, but I can’t justify the cost and hassle. I see their advantages, I guess I am old school, I maintain my brakes and bearings, and I stop every couple hundred miles, check pressures, hit the tires and hubs with a laser thermometer. I like them, it’s just a very low priority for me. I would consider putting them on the toad first if i was going that direction.
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL -
I purchased the PressurePro FX with 12 sensors. I was able to install 6 of the 8 on the coach’s wheels, and 2 wheels (outer drive wheels) required the valve stems to be swiveled about 90 degrees. I like the system overall, and now I am seeing that inner right drive wheel is losing pressure. Not yet sure if this is because of the PressurePro sensor leaking, a valve stem extension leaking, or I have a new leak in this tire. I am hoping it’s one of the first two. I just replaced the two front tires with new Michelins, and I am kicking myself for not asking to keep the two old ones for spares.
BTW, I used the National Tire Concierge tire buying service ($90 one-time membership fee), they set everything up with the installer for me. Main reason I went this way is they have a road-hazard warranty that is for 3 years and *not* pro-rated.
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Dish soap and water in a spray bottle will tell you if the sensor or valve stem or extension is leaking. You can do it with the bus on the ground, just move bus till the valve is near but not at the bottom of the inner wheel. Set the spray bottle on “stream” setting and spray away. Crawl around on the ground with a flashlight and you should see bubbles somewhere if it is leaking. If no leaks, there can spray same solution all over tire and tire rim junction. Don’t forget the part of the tire that is on the ground – will have to move the bus. The Pressure pro sensor can leak at the seam around the circumference, or where the brass part goes into the plastic. Should be rare on new sensor. Can alternatively test that for leaks by temporarily putting it on the tag to make it easier to see.
My recommendation is to get rid of the inner wheel valve extensions, even if they are not leaking, sooner or later they will. They may not have leaked without a sensor on them because they normally are not pressurized except when filling or checking pressure. When you screw the sensor on, the pin disengages the tire valve stem from the seat and you have multiple points where the system can leak. I had this happen to me, I ditched the extensions.
This tool will make it easier to work on the inner valve core while wheels are still on the bus, can be used for outers too if pointing the right way.
Make up a tool with a 12″ or so piece of 3/4″ pvc pipe and a glue type coupler, picture on prior post:
/threaddetails.asp?Category=General%20Discussions%3E&ThreadID=2709#23283
The pressure pro sensor fits right in the end of the coupler and you can screw it on and off the tire valve which should be set to point towards one of the holes in the outer wheel.
Regarding turning the outer valve stems, you can loosen up the nut and just turn the stem to point where you need it to be, then re tighten the nut – there is a spec for torque – it is a surprisingly high 10 foot pounds. MOST of the time the gasket between the stem and the inside of the wheel will remain functional, but if it is very old some chance it may disintegrate. Recommend you do not try this repositioning while in deep space, wait till you are in spaceport.
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David, thanks for the tips! Right now I have the PP sensor off, and I am going to check the pressure 24-hours after today’s check (with my air chuck). If I see no difference, then I can probably attribute it to the extension or the sensor (I bet it’s the extension).
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If it’s the sensor leaking it will be in two possible places. One is at the seam and the other is at the brass thread. I have seen 2 of these in the last 8+ years, it’s rare but does happen. Your leaking likely is the extension. Toss it in the trash and install the sensor with a 3/4 PVC pipe and coupling.
If it’s the sensor, easily replaced.
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