How can you tell which wheel goes on which corner?

[Rolfe]

I take it this is your first car with this type of system? It's perfectly normal for them not to be marked. In fact I have never seen any car with them marked.

Many people routine swap tyres front to rear (and sometimes left to right) so the markings would be wrong after the first tyre change anyway. Most garages will strongly advise that you fit the newer tyres to the rear of the car, which would mean swapping the front wheels to the back. (unless you wanted to pay to swap the actual tyres on all four wheels when just replacing two of them)

Also, as I said before, you certainly don't need to go to the dealer for every car when swapping wheels. If you do a TPMS reset (via the menu) on many cars they simply learn the new wheel location. My previous car didn't even need that, and would auto-detect if a wheel has changed location and re-learn after a set period of driving.

Unfortunately for you, I therefore imagine a lot of tyre fitters don't pay much attention unless specifically asked about it. Let's face it, so many cars have TPMS now, imagine if every car they did had the owner come back and complain. They'd soon have to adjust their process to stop it happening as it'd be a huge waste of their time.

I take it you had all four tyres changed at once? To be honest that's probably quite unusual in itself as normally the driven wheels wear at a faster rate.

Yes, I have not encountered this before, but then my last car was 14 when I finally had to get rid of it.

I would have thought that one would swap the tyres, not the wheels, unless I suppose an owner was doing it himself. Although I suppose I'm wrong about that, I'm thinking about the autumn/spring tyre changes. But even so, it should not be beyond the wit of man to devise a marking system that can be updated if the wheels are moved.

It's entirely normal around here for all four tyres to be swapped at once. I've been doing it twice a year for 12 years at least. Winters on in November, switch to summers in April. This was my switch to "winter tyres" although I've chosen to put all-seasons on this time. So this garage are doing this all the time.

So if the garage don't routinely mark the wheels, yes, it's going to be a huge waste of their time, and I hope they have to waste a ton of it next Friday. I suppose it's possible they did mark them, but somehow two wheels still got switched.

My last car had a system that seemed to be something to do with wheel rotation and whether all four wheels matched. I paid £25 for it as an extra when I bought the car! It simply flagged up that there was a problem, and it was also quite prone to false alarms, especially spring and autumn and every time the tyres were changed.

But I can't imagine that the MG4 is especially unusual in 2023 in having this system. I just assumed the garage would know what to do.

 

[PaulD]

I wouldn't have the foggiest idea how to check. But the garage are not normally a bunch of morons, so I think they will get it right this time.

Just for your reference in case you ever need to know, it's quite simple.

If you look at the tyre markings a directional one will have a clear arrow somewhere showing the required direction. An asymmetric tyre will have 'outside' written on one side and probably 'inside' on the other. (Obviously you can only normally see the 'outside' marking when the wheel is on the car.) If it has neither of those you it can be fitted any way around you like.

 

[Kithmo]

So the wheels are actually specific to one corner on the MG4 ?
I know they were on the ZS because the system on the ZS was a simpler system AFAIK.
I would have assumed that the MG4 TPMS would pick up the location of the tyres automatically, but apparently not.

 

[mg4mc]

So the wheels are actually specific to one corner on the MG4 ?
I know they were on the ZS because the system on the ZS was a simpler system AFAIK.
I would have assumed that the MG4 TPMS would pick up the location of the tyres automatically, but apparently not.

No, it's more expensive to fit a receiver in each wheel arch (which is what most self-learning systems have I think) than have one central one. And the 4 was built to a price.

 

[Rolfe]

No, it's more expensive to fit a receiver in each wheel arch (which is what most self-learning systems have I think) than have one central one. And the 4 was built to a price.

I'm actually surprised it has such a sophisticated system at all, being, as you say, built to a price.

 

[Rolfe]

Just for your reference in case you ever need to know, it's quite simple.

If you look at the tyre markings a directional one will have a clear arrow somewhere showing the required direction. An asymmetric tyre will have 'outside' written on one side and probably 'inside' on the other. (Obviously you can only normally see the 'outside' marking when the wheel is on the car.) If it has neither of those you it can be fitted any way around you like.

Thanks, that's very helpful.

 

[gazza487]

No, it's more expensive to fit a receiver in each wheel arch (which is what most self-learning systems have I think) than have one central one. And the 4 was built to a price.

Weirdly those type of systems it is actually a transmitter in 3 of the wheel wells. TPMS sensors can be triggered by a ping in the few hundred kHz range, all the sensors transmit (respond) on the same frequency which is the same as the central locking. Car demands a response from a specific tyre, when it gets it it knows where it’s from. They get away with 3 by a process of elimination.

To save money they hard code the TPMS into the car and there are procedures for a setup (different by make, some need a direct prog to the ecu some can be set to learn and you trigger the sensors in order a la Vauxhall). I keep threatening it but will update my autel which lists the methods by model on the tool and report back on the 4.

 

[Vingnut]

I realy do not understand the problem (I do but refuses to), when I change from summer to winter tyres and the oposit, I put a marker on each valvestem. LF (Left Front) LR (Left Rear), RF (Right Front and RR (Right Rear). I have markers for each wheel and each car I own when the wheels are stored, now cause the TPMS I will get valve caps marked LF / LR / RF / RR and the matter will be solved. Then I wil now when rotating the wheels from front to rear (have tyres with rotational direction) where the wheels realy are without messing with programing.

 

[Alex1985]

Back in the day (pre EV) TPMS was achieved by monitoring the ABS sensors which were referencing wheel rotation, if a tyre was underinflated it would rotate at slightly different rate than the others so the tyre causing the problem could be identified.

It would not take much to calibrate the rotational difference between the pressure in tyre and it’s rotational rate to give a readout of approximate tyre pressure.

There would also be no requirement to assign a wheel to a particular location as they could installed at any corner. It seems an unnecessary complication and expense to add pressure sensors to wheels if that is how they function.

 

[gazza487]

Back in the day (pre EV) TPMS was achieved by monitoring the ABS sensors which were referencing wheel rotation, if a tyre was underinflated it would rotate at slightly different rate than the others so the tyre causing the problem could be identified.

It would not take much to calibrate the rotational difference between the pressure in tyre and it’s rotational rate to give a readout of approximate tyre pressure.

There would also be no requirement to assign a wheel to a particular location as they could installed at any corner. It seems an unnecessary complication and expense to add pressure sensors to wheels if that is how they function.

I had the active type back in 06 on my Chrysler (it was such a pain learning about the infernal thing as nobody knew much about them). The rotational type seemed to come after that and is basically a function built into the ABS modulators (which monitor rotation at each wheel anyway) as a cheap way to get around needing a pressure monitoring system which is required by law. Not sure which was first released tbh.

Having had both (oddly on my VERY economy diesel Kia Rio they chose to fit active tpms without a display) the trials of the sensors are worth it imho. The rotational type as per my MG6 is less than stellar, all tyres can go down and it won’t do anything, hit a bump and it’ll moan (same for my brothers newer Kia). Getting a “pressure” reading from the differential in rotation would not be easy as the system only measures the change in rotation so at best you may get a very inaccurate change in the pressure. The reset button just sets the baseline in rotation.

Advice to OP and all is look into the Autel tpms kit and arm yourselves for when it’s needed along with a decent pressure gauge and pump because the active type with sensors will kick off when the weather changes. I have no affiliation to Autel btw but only had good experience with their kit

 

[gazza487]

Right I’ve updated my autel TS408 to know what an MG 4 is. Good and bad news - there is no procedure to simply learn new sensors, they must be told to the cars ECU and my TS408 can’t do that - you need the slightly higher end models that will code new sensors to the car via OBD. Upside I’ve pulled all the sensor IDs for future so I could “clone” the original sensors should one die without extra kit and itd make it a doddle should I be in OPs position. For giggles here’s the data from my car (it WILL be different for yours).

If anybody Tamworth area would like the above pulling for future reference for their vehicle FOC - hit me up

 

[Rolfe]

I realy do not understand the problem (I do but refuses to), when I change from summer to winter tyres and the oposit, I put a marker on each valvestem. LF (Left Front) LR (Left Rear), RF (Right Front and RR (Right Rear). I have markers for each wheel and each car I own when the wheels are stored, now cause the TPMS I will get valve caps marked LF / LR / RF / RR and the matter will be solved. Then I wil now when rotating the wheels from front to rear (have tyres with rotational direction) where the wheels realy are without messing with programing.

The problem is that I expected the garage who were doing the job for me to have the sense to do whatever it took to make sure the wheels were replaced in the same locations they came off.

They didn't.

 

[Rolfe]

Well, Caliban is currently spending the night in the garage forecourt half a mile away, waiting for this to be fixed in the morning. I called in this afternoon to pay the bill for the new tyres, and had a bit of a moan about it. I got a bit of shuffling, and, well this is a very new system. I told them the right-hand wheels had definitely been switched, and I had no idea about the left-hand ones. There followed a lot more technobabble about re-coding the wheels.

So I went home, had lunch, then went out and let some air out of the near fore tyre. Took the car half a mile along the road, and the pressure displayed for the near fore dropped to 2.2 BAR. (Although there was no low-pressure warning, strangely enough.) Result.

So I went back to the garage saying here you are, I'm leaving the car, fix it. To my admittedly simple understanding, that would seem to involve nothing more than swapping the front and rear wheels on the right-hand side back again, and inflating all the tyres to the correct pressure of 37 psi or 2.5 BAR. And please do that, because they were all over the place the first time you gave me the car back, and one of the tyres is currently quite soft.

So we'll see if it actually is that simple.

 

[Deleted member 11291]

So I went home, had lunch, then went out and let some air out of the near fore tyre. Took the car half a mile along the road, and the pressure displayed for the near fore dropped to 2.2 BAR. (Although there was no low-pressure warning, strangely enough.) Result.

A bit of vet talk slipping into the conversation…?

 

[gazza487]

Well, Caliban is currently spending the night in the garage forecourt half a mile away, waiting for this to be fixed in the morning. I called in this afternoon to pay the bill for the new tyres, and had a bit of a moan about it. I got a bit of shuffling, and, well this is a very new system. I told them the right-hand wheels had definitely been switched, and I had no idea about the left-hand ones. There followed a lot more technobabble about re-coding the wheels.

So I went home, had lunch, then went out and let some air out of the near fore tyre. Took the car half a mile along the road, and the pressure displayed for the near fore dropped to 2.2 BAR. (Although there was no low-pressure warning, strangely enough.) Result.

So I went back to the garage saying here you are, I'm leaving the car, fix it. To my admittedly simple understanding, that would seem to involve nothing more than swapping the front and rear wheels on the right-hand side back again, and inflating all the tyres to the correct pressure of 37 psi or 2.5 BAR. And please do that, because they were all over the place the first time you gave me the car back, and one of the tyres is currently quite soft.

So we'll see if it actually is that simple.

Aye, having looked through it in prev posts and confirming there is no self learning your airing up/down vs the indicated location on the display should be just the ticket.

 

[Rolfe]

I just hope they keep it simple and just switch the wheels back, rather than trying to get clever and re-coding them.

 

[Ejaydee]

Luckily here, the local tyre fitters tend to take one wheel off at a time, change the tyre and then put back on the car where there is just one space to fit it. Simple really, but I guess they may have had problems like yours previously.

 

[Rolfe]

I just collected the car and all seems well, except that although all tyres were showing 2.5 BAR when I collected it, the two rear ones went down to 2.4 not long after I started driving. Hmm. Will keep an eye on this.

 

[siteguru]

The car screen pressures can only be used as a guide ... physical checks need to be made on a regular basis (as with any other car). Have you bought that pressure gauge yet?

Here's a cheap as chips option:

Amazon product ASIN B00K66WY8E

 

[Rolfe]

I'm waiting till I find my Dad's old one at the back of a drawer somewhere...