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True, and there's a very good reason for that, which doesn't carry over to the gauge: The Seiko is purely digital with no moving parts.

I trust cheap electronics to have reasonably consistent precision over time. That trust doesn't extend to cheap mechanicals. I'd bet that my decade-old pencil-type depth gauges have developed at least 0.1mm (not 0.01mm) of slop by now. That digital widget is fundamentally the same design with the addition of electronic measurement of the pin's position. The cost and quality of that basic mechanism is probably similar between the two; I'd expect their reliability over time (or lack thereof) to be similar as well.

But as you noted, the trend's the thing, and the trends you're looking for are well above the 0.01mm noise anyway.
I bought a bunch of Made In USA pencil depth gauges 30 years ago, pre-Interwebs. I eventually wore all but one out, which is still in the wrapper. After a few years, the plunger doesn't stay put in the cylinder. The ones they sell now are identical,,but Made in China.

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Thanks to all for the comprehensive range of responses.

Firstly to andrewwynn, I found every spoke had different numbers & letters embossed on the inside. All I got was brake dust all over my hands & a little wet from a summer thunderstorm here in Melbourne Australia! I checked the online data base recommended by QSilver7 which listed the wheels as BMW LA wheel M double spoke 435(S2PHA....11JX20 ET:35 & 10JX20 ET:40. I'm unable to find their RFT/nonRFT status. I did notice amongst the fluids in edycol's photo of his spare tyre, a bottle of sherry cask matured whiskey which would be extremely helpful in dealing with a flat.

Thanks again to all for the information ...... I've got maybe 5000Km left in the RFTs before having to make a decision.
Are you sure it doesn't say 10JK20? I can't find JX flange style.

Code:
 Flange type is designated by a classification system using one or two letters. The most commonly used flange heights are J= .68"(17.3mm), JJ=.69"(17.5mm), JK=.71"(18mm), K =.77(19.5mm), and L = .85"(21.6mm).
Less than 1mm different from J to JK

S2PHA I don't know what that means and there should be something to describe if there is a internal bump or not that holds the bead of the tire "locked in"



Looks like you read correctly. You need to find out if the flange profile is not compatible with non RFT.

The photo looks like there is a bead locking hump but all my wheels have had that
 

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So, RFT are useful if there is shop close by. In the West, where there is no shop for xxx miles, spare is irreplaceable. Even if I have RFT (I have them still on my minivan in summer and my E90 in summer for daily driving) I carry spare when doing long distances. I70 once in UT? There is a stretch of more then 100mls without exit and poor cell signal. I am not going to ski (and I ski twice a week) without spare. Changing tire in blizzard is piece of cake compared to failed RFT bcs. no shop close by. And, existing shops are not going to have your tire size. There is no replacement for spare. Yes, it might work on I95, I94 in Chicagoland, or I5 between San Diego and LA. Here in the Rockies? Spare with bottle of single malt when skiing!



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That's where I keep my emergency bourbon.

I have always carried a spare in my e53 and I will get one for my e70.

The best save my ass story was the blizzard one. With inches of fresh snow nobody drove on yet, I couldn't tell I had a flat and i drove the tire to destruction.

When I stopped on the freeway to check it was positively horrible blinding snow blizzard conditions so I just hopped back in the car and drove a few miles to where I had a well illuminated covered area to pull out 5-600#?of tools covering my spare and swap that on. Changing a driver side tire on a freeway in zero visibility is risking your life. At least every couple years you read about somebody in Chicagoland that got killed while making an emergency stop on the freeway.

RFT for me just means a way to drive off the freeway to a better place to change the tire.
 

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2012 X5 E70 M50d with RFTs & a space saver spare.

I got a TPMS alert 200 meters from a service station & found a nail in the center of the R rear tyre tread. Only lost 5psi....... topped up the pressure & drove the short distance home without further loss. Independent tyre repair shop was able to fix it next day. When I raised the topic, I was told I couldn't replace the RFTs with non RFTs as I had "RFT wheels". My understanding was that RFTs need a second rim in the wheel & can't be fitted to a conventional rim but that a non RFT can be fitted to a RFT wheel. Can anyone confirm this?
 

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I am 80 years old and am unaware of a special rim required for run flat tires. Early tires had an innertube. Many years ago they increased the rim and tire edge and did away with the innertube. Later, early run flats had an inner type flap a lot like an inner tube. Air pumped into the wheel rim went through a one way valve in the flap so there were two air chambers. If the outer chamber was pierced, the inner chamber still held the air since the tire was only partially deflated. Later they did away with the flap and increased the thickness of the tire side wall on run flats. Todays run flats run on the tire tread held in place by the thicker side wall. There is potentially no air in the tire.

The reason today's run flats get half of the mileage of a standard tire is that the thicker side wall makes the tire run at a higher temperature. Heat increases tire ware!

I have a 2009 X5 4.8i. The first two tire replacements were run flats. I then switched to standard tires and just put on my second set at 130,000 miles. I am now getting 40 - 50,000 miles on my tires. I do insist on high speed rated tires and quiet tread with a short stopping distance. I don't notice a difference in how the car handles but honestly, I don't drive faster than 90 MPH. If I take curves at high speed the tire edges wear. However, I had similar wear on the edges with run flats. The car came with run flats and I use the rims it came with. I don't see a second wheel rim but I don't know if there is anything special about the rim edge.

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2021 X3 M40i Glacier Silver Metallic w/Cognac leather, M-sport suspension, M-differential
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2012 X5 E70 M50d with RFTs & a space saver spare.

I got a TPMS alert 200 meters from a service station & found a nail in the center of the R rear tyre tread. Only lost 5psi....... topped up the pressure & drove the short distance home without further loss. Independent tyre repair shop was able to fix it next day. When I raised the topic, I was told I couldn't replace the RFTs with non RFTs as I had "RFT wheels". My understanding was that RFTs need a second rim in the wheel & can't be fitted to a conventional rim but that a non RFT can be fitted to a RFT wheel. Can anyone confirm this?
Recently due to the winter, I removed my RFT's and replaced them with Non-RFT's. My BMW dealership made the change so if there were any problems with RFT rims, they would have told me and charged me for replacing the rims as well. I did this on my 2021 X3M40i. Have had no problems since the change.
 

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That's where I keep my emergency bourbon.

I have always carried a spare in my e53 and I will get one for my e70.

The best save my ass story was the blizzard one. With inches of fresh snow nobody drove on yet, I couldn't tell I had a flat and i drove the tire to destruction.

When I stopped on the freeway to check it was positively horrible blinding snow blizzard conditions so I just hopped back in the car and drove a few miles to where I had a well illuminated covered area to pull out 5-600#?of tools covering my spare and swap that on. Changing a driver side tire on a freeway in zero visibility is risking your life. At least every couple years you read about somebody in Chicagoland that got killed while making an emergency stop on the freeway.

RFT for me just means a way to drive off the freeway to a better place to change the tire.
Why your TPMS didn’t warn of failed tire?


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Why your TPMS didn’t warn of failed tire?


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Because I had an '01 with no TPMS.

Drove cars for 100s of 1000s of miles before tpms was a thing. I know to check my tire pressure regularly. TPMS became mainstream because people are too lazy or too ignorant to maintain their tires.
 

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I'm carrying around a full-sized spare in my E70 right now, which means my cargo space is compromised. I'm debating getting a compact spare that will actually fit underneath, but then I consider how much towing I do. A compact spare while towing would only get me out of an immediate problem, but I'm not going to be able to continue my journey without finding a tire soon. Of course, being an AWD vehicle, you don't want to just bop into Discount Tire and have them install a new tire to go along with your other 3 tires sporting 7/32" of tread. A good compromise may end up being getting a compact for everyday use, but tossing the full-sized into the cargo area any time we're towing or just travelling far from home.

I've become an advocate of using a 5-wheel rotation on my AWD vehicles. That way, in the event of a non-repairable injury to a tire, you can simply switch to a 4-wheel rotation for the remainder of the tread life. Lots of people end up buying 4 new tires after ruining one on a curb or similar.

AM.
 

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I'm carrying around a full-sized spare in my E70 right now, which means my cargo space is compromised. I'm debating getting a compact spare that will actually fit underneath, but then I consider how much towing I do. A compact spare while towing would only get me out of an immediate problem, but I'm not going to be able to continue my journey without finding a tire soon. Of course, being an AWD vehicle, you don't want to just bop into Discount Tire and have them install a new tire to go along with your other 3 tires sporting 7/32" of tread. A good compromise may end up being getting a compact for everyday use, but tossing the full-sized into the cargo area any time we're towing or just travelling far from home.

I've become an advocate of using a 5-wheel rotation on my AWD vehicles. That way, in the event of a non-repairable injury to a tire, you can simply switch to a 4-wheel rotation for the remainder of the tread life. Lots of people end up buying 4 new tires after ruining one on a curb or similar.

AM.
Tire Rack will shave a new tire down to match your old tires for about $35. It delays the tire's arrival by a few days, though. Range Rovers offers a full-size matching spare (for that 5-tire rotation pattern) that still fits under the cargo floor. I hope BMW eventually buys Range Rover back and all the RR's moving parts are BMW.
 

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I'm planning to pick up one of those full height skinny spares BMW has for e70. About $200 includes tire, wheel, jack. (but not mounting).

My new to me e70 has room for it under the trunk floor I believe.
 

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Because I had an '01 with no TPMS.

Drove cars for 100s of 1000s of miles before tpms was a thing. I know to check my tire pressure regularly. TPMS became mainstream because people are too lazy or too ignorant to maintain their tires.
Well I know cars without TPMS, trust me.
RFT’s cannot be used safely without TPMS. So, even if you had option to buy RFT I don’t think any tire shop would agree to install.


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Well I know cars without TPMS, trust me.
RFT’s cannot be used safely without TPMS. So, even if you had option to buy RFT I don’t think any tire shop would agree to install.


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That is supposition (can't be used safely without TPMS). It's incorrect.

I drove 70,000miles or so with several tire failures with RFT and no TPMS. If you are just moderately aware of your cars feedback you will know when a tire loses air pressure.
 

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My 04 E53 just had the old FTM that relied on wheel speed sensors. I was surprised how well it (FTM) worked the one time I had a flat on that vehicle. In fact, I knowingly announced that it was apparently giving a false signal when the light came on.... until about a minute later when I felt that squirm you get with a flat tire. I carry a 12V compressor and a plug kit at all times, and 98.3% of the time, I can fix a flat and be on my way. That day, I did a number on the tire with a really large gash. An hour later, I got a flat on my jet ski trailer (failed rubber valve stem). What are the odds of getting two flats in one 2-hour trip (and neither repairable)?

AM.
 

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That is supposition (can't be used safely without TPMS). It's incorrect.

I drove 70,000miles or so with several tire failures with RFT and no TPMS. If you are just moderately aware of your cars feedback you will know when a tire loses air pressure.
There are A LOT of “if’s” there. I personally would not do it even if someone paid me. I have kids in my car. I can drive and look what my 2yrs old did now and completely neglect potentially weird behavior of RFT. And even if I catch it, how do I know if there is no internal damage?
IMO, RFT without TPMS is putting yourself and others in danger. There is no any way around that.


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It's not really different from saying driving with non RFT without TPMS is dangerous. There really is no extra risk. When a tire fails it fails. 100+ years of driving without TPMS the world survived.

The point of the combination is to avoid tire damage by catching the failure early. Every time save once, my tire was destroyed and needed to be replaced the other time the valve stem failed and the tire was fine.

One of the times it would have been possible the tire would have been saved with TPMS to alert me sooner but there was never any significant danger to myself from driving on a zero pressure tire designed to drive on zero pressure.

You can assume if the tire was driven on arrival zero pressure it just "Gave its life" for you. It needs to be replaced.
 

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It's not really different from saying driving with non RFT without TPMS is dangerous. There really is no extra risk. When a tire fails it fails. 100+ years of driving without TPMS the world survived.

The point of the combination is to avoid tire damage by catching the failure early. Every time save once, my tire was destroyed and needed to be replaced the other time the valve stem failed and the tire was fine.

One of the times it would have been possible the tire would have been saved with TPMS to alert me sooner but there was never any significant danger to myself from driving on a zero pressure tire designed to drive on zero pressure.

You can assume if the tire was driven on arrival zero pressure it just "Gave its life" for you. It needs to be replaced.
You have RFT that are so stiff that they can lose half a pressure and still drive ok.
You don’t have to lose all the pressure to exert fatal damage to tire. And that damage can come back to bite you later when you fix tire and drive 80-90mph.
Yes, world was driving and still drives without TPMS. And yes, in that same world under pressure tires were and still are huge safety problem. In tire industry overinflated tires are not an issue, under inflated are. And big one. People die every day bcs. their tires were damage for various reasons and they never saw it.
There is a reason why no tire shop would ever install your RFT without TPMS. Actually on your RFT it says that they should not be mounted without TPMS. It is single most important safety item on the car.


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you cannot fix and use RFT if you ever drive on it with low pressure. Same applies to normal tires. Driving with low pressure will damage the internal structure.
 

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you cannot fix and use RFT if you ever drive on it with low pressure. Same applies to normal tires. Driving with low pressure will damage the internal structure.
But you telepathically know when RFT started to lose air? Listen, you can justify to yourself as much as you want. I thought that warning not to mount RFT without TPMS is ridiculous. But I see now it is necessary.


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