Question on 1st Tire Rotation

[BVGeezer]

Well, I have a tire cover on my spare. Does that make a difference to what you said about sun rot?

No clue to answer your question. Somebody here with more knowledge will answer. My guess is that the tire ages out from a variety of environmental and manufacturing factors besides UV.

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[Terrymo]

But why, please.

As @Roky and others have already answered you get 20% more tire wear out of the tires. If it’s a pavement princess it probably doesn’t matter as much.

 

[Terrymo]

Hope that helps!

Just make sure you follow this sequence each time you do a rotation

 

[Terrymo]

From my owners manual. It’s not worded like one of the 10 commandments. Seems like maybe you’ve already made up your mind.

 

[Ratbert]

I freely admit that it might not explicitly say so in the manual, but do all 5. You'll get ~20% more life from your tires and will actually be able to use your lockers without worrying about screwing anything up with one tire being so much larger than the rest.

The alternative is to waste ~20% of your tires. You'll most likely get something different next iteration (e.g. KO3s instead of KO2s, etc), but even if you don't that tire is going to have aged.

 

[BXFXJeep]

5 rotation means you know that spare is always in good working order.

Some people do 4 because their spare doesn't have any rubber, someone stole the rubber maybe, it's Canada strange happens here.

 

[Ratbert]

To my rookie mind the rotation is to make for even wear on the tires you use all the time. The tire on the back is supposed to be a spare, not an everyday tire. putting it into the rotation only complicates things.

by keeping the rotation to the 4 you always use you assure even wear.

Let's change that a bit:

By keeping the rotation to 5 you always ensure even wear while also getting ~20% more wear.

 

[Terrymo]

5 rotation means you know that spare is always in good working order.

Some people do 4 because their spare doesn't have any rubber, someone stole the rubber maybe, it's Canada strange happens here.

SoCal as well

 

[sunset]

Seems like maybe you’ve already made up your mind.

Not at all. Still encouraging responses, thanks.

 

[sunset]

Say, on a different topic, talking to my brother on the phone right now, he asked an interesting question about TPMS. Since all 5 tires have stems that report, why do they only display four of them? Seems it might be good to know if your spare tire lost pressure. It's quite near the rear tires so I wouldn't think it's out of range from reporting, had they provided the software to do so.

 

[azwjowner]

Say, on a different topic, talking to my brother on the phone right now, he asked an interesting question about TPMS. Since all 5 tires have stems that report, why do they only display four of them? Seems it might be good to know if your spare tire lost pressure. It's quite near the rear tires so I wouldn't think it's out of range from reporting, had they provided the software to do so.

Because TPMS is mandated by law, but only for wheels in use, and adding a fifth sensor costs money, which means less profit for Jeep.

Incidentally, I just pump up my spare tire to the sidewall max PSI so I don't have to check it but once per year. If I ever have to use it, it's easy to deflate to the correct amount. (I also have an air compressor in case it actually was too low).

 

[sunset]

Because TPMS is mandated by law, but only for wheels in use, and adding a fifth sensor costs money, which means less profit for Jeep.

The cheap bastids. LOL

> but only for wheels in use,

I wonder how the detection mechanism knows which of the five reporting stems to ignore. If it senses motion in the four stems as the tires rotate, maybe, while a fifth signal is motionless in comparison?

 

[Terrymo]

Because TPMS is mandated by law, but only for wheels in use, and adding a fifth sensor costs money, which means less profit for Jeep.

Incidentally, I just pump up my spare tire to the sidewall max PSI so I don't have to check it but once per year. If I ever have to use it, it's easy to deflate to the correct amount. (I also have an air compressor in case it actually was too low).

There is a TPMS sensor in the factory mounted spare but it is not read by a chassis sensor/ considered by the computer until it is placed in one of the 4 tire positions. My understanding is there are only 3 chassis sensors unless I’m mistaken.

 

[azwjowner]

So you believe one of the tires does not have TPMS?

There is a TPMS sensor in the factory mounted spare but it is not read by a chassis sensor/ considered by the computer until it is placed in one of the 4 tire positions.

No, the tire has the sensor. The vehicle doesn't read the sensor (on the spare).

Although, it might also be because TPMS sensors are shutting off when not spinning to save power. And the spare doesn't spin! So it might be impossible, practically speaking.

Some more info here: https://www.jlwranglerforums.com/fo...eceiver-sensor-wheres-it-located.56385/page-2

 

[sunset]

There is a TPMS sensor in the factory mounted spare but it is not read by a chassis sensor/ considered by the computer until it is placed in one of the 4 tire positions.

Yes. I've already asked this but in a different way, but I'll ask it anew based on how you said that.

How does the computer not read the 5th signal? I bet it sees it but discriminates it from the other four.

Otherwise, if one of the four stems ever fails, there would now be just four signals to detect, a perfect match for four stems to display, yet it still knows to ignore the spare stem.

Yeah, I think it sees four spinning stems and one static stem. Could that be why upon leaving my garage it takes half a block before the PSI readings update? To give the computer time to sense which 4 of the 5 stems are spinning?

But, wait, it also knows to which corner of the car each spinning stem belongs. This suggests to me that it sees zones, perhaps four zones, one for each active tire, while no fifth zone exists where the spare would be. And that's how it ignores the spare stem. And when you rotate tires, the stem of each tire simply shows up in its new zone. Guessing here.

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