Running a TPMS in the spare

[HTX1811]

After getting a flat this past weekend and running the smaller size spare for a few days waiting on the replacement tire to arrive, my truck was not happy with the size difference. Likely only about a 1.5"difference in diameter but enough for a few messages to pop up and the traction control warning to stay on.
So, I ordered a used factory 17" rim (factory spare rim is only 16" and cannot get an exact tire profile and diameter match) and the same tire as what's on the truck, Nitto Ridge Grappler 255/80r17.
My question is if I put a TPMS on the spare, will it interfere with the other sensors when not mounted, then work as designed when mounted.
Discount tire says unless the 2019 Ranger is different than all other Fords, it is not designed to run 5 TPMS and the spare will likely interfere with the mounted TPMS. One member on here said he has been running a 5th TPMS for a while with zero issue. I have no reason to doubt him but when Discount told me this today, I thought I would post it to the board.
I told him that some board members are running a 5th TPMS with no issues and he said, maybe the Ranger is set up for 5 TPMS but he has yet to experience it.

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[armoredpig]

I think the sensors on the truck side relearns which wheel is mounted nearest to it--since when I got new wheels and tires, after a few miles, the sensors reflected it's respective tire pressure in the correct locations.

However, that's not to say it will work. If the system can register 5 sensors, I think you'll be ok as the system will recognize which is where after a few miles.

 

[HenryMac]

Why not just put a spare tire on the spare wheel that's the same outside diameter as your Nitto Ridge Grappler 255/80r17's?

 

[HTX1811]

Why not just put a spare tire on the spare wheel that's the same outside diameter as your Nitto Ridge Grappler 255/80r17's?

I could get close to the same diameter on a 16” rim vs the 17” size but not close enough for my OCD. Width wise would have been different.
Absolutely overkill but I’m happy with it.
The reason for the TPMS is so not to have to change to the spare then take it off again. Just throw the spare on, get flat fixed and mount that tire under the truck as the new spare.

 

[charwest]

The reason for the TPMS is so not to have to change to the spare then take it off again. Just throw the spare on, get flat fixed and mount that tire under the truck as the new spare.

or for those without flats: include the fifth wheel (matching spare wheel and tire) in the tire rotation. by my rough calculations, if you are running expensive tires this would basically pay for the price of the fifth wheel by extending tire set life a theoretical 20%.

that was my plan, but if the lack of TPMS or TPMS errors makes it a headache i will need to reconsider.

 

[slowmachine]

After some time doing this (5 matching wheels and tires with sensors) I doubt that the Ranger can actually see five sensors. The one in the spare position goes to sleep, and the truck no longer sees it until it is reactivated by rotation. It's a fine point that makes no difference in actual usage, but I was convinced at the beginning that the truck could see the fifth sensor all the time, and no longer believe this to be true. I believe now that the dash display continues to show the sensor data in memory for the tire that is moved into the spare position until that data is replaced by a new active sensor, rather than continuing to track the inactive sensor.

 

[y2krtaf]

Been running 5 wheels with sensors for about 5 months,and no issues.
‘Discount is wrong.
‘The pickups on vehicle are located in a close proximity to the wheel,I don’t see it being an issue unless that particular wheel sensor dies,and maybe,it has enough strength on a rear axle to to pick up the spare..
‘Now playing in Forscan,I have noticed that if the truck came with a 5th on vehicle pickup,we could monitor the spare.

 

[GTGallop]

Does a full size off road spare fit under the truck?

 

[charwest]

Does a full size off road spare fit under the truck?

my 32" tire fits (255/75/17). i have read here that a 33" fits. i have a steel spare wheel but cant see any reason why a standard wheel would change anything.

 

[LurchOR]

After some time doing this (5 matching wheels and tires with sensors) I doubt that the Ranger can actually see five sensors. The one in the spare position goes to sleep, and the truck no longer sees it until it is reactivated by rotation.

Bingo! TPMS sensors don't transmit until they sense rotation; otherwise the battery life would suffer.

 

[y2krtaf]

Does a full size off road spare fit under the truck?

Have a 33 under mine.

 

[GTGallop]

Bingo! TPMS sensors don't transmit until they sense rotation; otherwise the battery life would suffer.

Then why can my Ford App give me an updated Tire Pressure at 2:30 AM that's different than when I parked it a 5:00 PM?

 

[slowmachine]

Then why can my Ford App give me an updated Tire Pressure at 2:30 AM that's different than when I parked it a 5:00 PM?

Good question. AFAIK, no manufacturer publishes the details of how their systems work. I know that it is possible to “wake” a sensor with diagnostic tools, like the popular Bartec line, so it should be possible for the Ranger’s electronics to do the same.

 

[HTX1811]

Then why can my Ford App give me an updated Tire Pressure at 2:30 AM that's different than when I parked it a 5:00 PM?

I would guess it’s the last known pressure when it was active. After all the system is designed to give you a warning if the vehicle is moving not while sitting with the engine off. Here’s a test. Check all 4 pressures when you get home. Then air down one tire say 30 minutes to an hour after the truck has been sitting. Then update and see if it reads the same as when you parked or the lower pressure.

 

[HenryMac]

Then why can my Ford App give me an updated Tire Pressure at 2:30 AM that's different than when I parked it a 5:00 PM?

Are your wife or kids out cruising while you are sleeping?

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