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02/2012 X5 35d M57Y CPO 116K miles NOKIAN WR G3 30K miles
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RIght. But what if you take tread measurements, accurate to 0.0000001", and these show perfectly even wear- yet they wallow.

More pressure?

Or maybe sidewall stiffness cannot be independently controlled by fill pressure as you indicate...
Dig the tyre techie talk “adhesion over discontinuities”
 

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RIght. But what if you take tread measurements, accurate to 0.0000001", and these show perfectly even wear- yet they wallow.

More pressure?

Or maybe sidewall stiffness cannot be independently controlled by fill pressure as you indicate...
What if? What if? What if?

I actually measure my tread depths to 0.001" For Frau Putzer's G01 X3 30i, the recommended <100 MPH pressures are 32 PSI in the front and 35 PSI in the back. At 39 PSI all around, I'm finally getting almost even tire wear due to pressure. For the last ~8k mile rotation stint, the sides channels of the front tires wore 0.13/32" more than the two middle channels (under inflation). The middle channels on the rear wore 0.9/32" more than the side channels (slight over inflation). The four-tire average was 0.02/32" more wear on the sides. With four-tire rotation patterns, that 0.02/32" is the relevant metric.

The only tires I've ever seen wear more in the middle at the recommended <100 MPH pressures on a BMW were the rear 255/40-18 Michelin Pilot Sports on my E46 M3.

I have the master broadcast sheet for Frau Putzer's G01 X3 30i listing all the internal options, over 60 of them. A special non-run-flat-tire suspension isn't one of them.

The OE Goodyear LS2 run-flats on my 535i exhibited massive under-inflation wear patterns at well over the recommended pressures (35 PSI front and 39 PSI rear for <100 MPH). My new Michelin PS 4S non-run flats have a four-tire average of 0.06/332" more wear in the middle channels at 38 PSI front and 40 PSI rear for the first rotation stint. That's fine, because the two middle channels came about 1/32" deeper for the first rotation stint. After eight rotation stints, the middle channels should only be about 0.5/32" deeper than the side channels.

Uncle Dougie and Ard are mad because I'm on their Interwebs. They are the self-proclaimed final experts on everything.
 

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Even wear is a great way to determine the best pressure.

I just started doing 1/64" depth measurements and after the first set of measurement car totaled by deer

So I kept the tires and the replacement car has decent tires I won't have to swap over the Dunlops at least until next winter
 

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Even wear is a great way to determine the best pressure.

I just started doing 1/64" depth measurements and after the first set of measurement car totaled by deer

So I kept the tires and the replacement car has decent tires I won't have to swap over the Dunlops at least until next winter
Here's the schnizzle of tread depth gauges, about $15 on the Interwebs. The same gauge comes in different colors and brands. What makes this one better is the skinny probe and that the probe is not spring loaded like a machinist's depth gauge usually is. With the high resolution (0.001" or 0.01mm) you can see trouble before it sees you.

Computer data storage Measuring instrument Tire Font Rectangle


It's hard to get good readings when the tires are still on the car. I do my measurements during tire rotation. The resolution is so high that I've started taking two measurements in each channel, e.g. one near the "M" in "Michelin" and one 180° from that.
 

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I stumbled across an automotive blogger (Colin Austin) & SA who writes,

"...However, it should be known that BMWs are designed with softer suspension spring rates to compensate for the stiff sidewall of factory runflat tires, changing to non runflats can result in sometimes undesirable floaty ride, not the connected-to-the-road feel that BMW engineers strive for."

I wonder if there is truth in that statement?
No.
But, there are other components that are made from different materials to limit NVH. Mostly trick is in shock mounts and strut mounts. When people upgrade their suspension for various reasons, OE mounts are first to go out.
Next are various bushings. That is why there is whole industry behind polyurethane bushings.
Interestingly, stiffer mounts are much cheaper than BMW ones. One of the most popular upgrade on E90 are Monroe rear shock mounts: $9.
All those upgrades are worth every penny once you get rid of RFT garbage.


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Recently changed from RFT to non on wife's 50i e70.

Noticed a slightly softer ride, no significant change in the turn in or understeer but with e70 the road feedback already muted a lot compared to the e53.

I'll prob know much better in about a year.

I'm about to acquire an e70 with RFT mounted and plenty of tread so I will run out those tires. I may switch to my winter tires next fall that are non RFT and I'll definitely share my findings.

If I could find a similar deal on my favorite brand/model in RFT I would stick with them but I found them almost half off in non RFT model so that's why I bought them.

2 month later my car totaled but a deer. Kept the new tires when I turned over the car.
All you need is several upgraded mounts and polyurethane bushings in thrust arms.
RFT’s are junk. It is additional unsprung weight. Instead of stiffening vehicles suspension where it should be stiff: suspension components; they had to soften those components bcs. tires are stiff.


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RFT have saved my ass on three occasions. Regardless of the handling trade off there is plenty of solid argument on the "pro" side.

Not having to change a spare in a blizzard out of cellular coverage at 2am in the near wilderness made me a solid fan. From a standpoint of safety in regards to getting you to a better place to deal with a flat, that's the entire point in my opinion.

If you aren't pushing the car near its limits and just cruising down the highway, it's pretty priceless to decide when and where to deal with loss of tire pressure.

Three times my life was made far far far better at the moment due to having RFT at the time. No argument can be made to say anything would have been better in any way on those three occasions.

Dealing with a flat at those times at the moment of failure would have been an absolute horror show vs. literally no big deal.

Yours mileage may vary. Maybe you are ok with unloading and loading 700# of tools in a blizzard in the wilderness to change a tire. That is a horror show for any normal person.
 

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RFT have saved my ass on three occasions. Regardless of the handling trade off there is plenty of solid argument on the "pro" side.

Not having to change a spare in a blizzard out of cellular coverage at 2am in the near wilderness made me a solid fan. From a standpoint of safety in regards to getting you to a better place to deal with a flat, that's the entire point in my opinion.

If you aren't pushing the car near its limits and just cruising down the highway, it's pretty priceless to decide when and where to deal with loss of tire pressure.

Three times my life was made far far far better at the moment due to having RFT at the time. No argument can be made to say anything would have been better in any way on those three occasions.

Dealing with a flat at those times at the moment of failure would have been an absolute horror show vs. literally no big deal.

Yours mileage may vary. Maybe you are ok with unloading and loading 700# of tools in a blizzard in the wilderness to change a tire. That is a horror show for any normal person.
It's a probability game. I've driving about one million miles over my life. I'm old and I was an inner-city courier in college. All of my punctures, maybe 25, have been slow leaks. I've only had one blowout, and that was caused by a bad rubber valve stem. TPMS has eliminated rubber valve stems on BMW's.

I had a spare when I had my blowout, and I was on my way in 30 minutes.
 

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You make a very interesting point.

It's very true that most leaks will be slow and it seems quite ironic that TPMS has become tied to RFT when, if you have TPMS, It likey eliminated the utility of the RFT in many cases as you will notice the slow leak and can pull over and address it.
 

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I have three vehicles in the garage with RFTs. I like the idea of not dealing with a flat tire on the side of the road.

No doubt, they ride rough!
 

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I never had a "ride rough" issue but I do usually have 600# of ballast to smooth out the ride.

Went to some non RFT on wife's 50i and did notice a slight improvement in road feel but nothing substantial
 

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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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3er + 3er + 4er = 10er, Bimmers?!
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Here's the schnizzle of tread depth gauges, about $15 on the Interwebs. ... With the high resolution (0.001" or 0.01mm) you can see trouble before it sees you.

The resolution is so high that I've started taking two measurements in each channel, e.g. one near the "M" in "Michelin" and one 180° from that.
You'd be better off taking six: three at each location, averaged; or discard high & low. That's good practice even with a simple analog pencil-type gauge.

0.01mm resolution (10µm) on a $15 gauge is comical and I'd be highly skeptical that it was reliably precise or accurate to that degree. Even if it is...so what? Wear measurement at 10µm resolution on a passenger-car tire is genuinely useless information. A typical high-performance tire sheds that much rubber in 50 miles. With monitoring intervals of 5,000mi you'd easily spot trends at one-tenth the resolution (0.1mm). So, use a gauge with 0.1mm resolution and save the effort of recording/rounding one digit of noise. ;)

The extra digit probably looks cool in your spreadsheets, though.
 
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You'd be better off taking six: three at each location, averaged; or discard high & low. That's good practice even with a simple analog pencil-type gauge.

0.01mm resolution (10µm) on a $15 gauge is comical and I'd be highly skeptical that it was reliably precise or accurate to that degree. Even if it is...so what? Wear measurement at 10µm resolution on a passenger-car tire is genuinely useless information. A typical high-performance tire sheds that much rubber in 50 miles. With monitoring intervals of 5,000mi you'd easily spot trends at one-tenth the resolution (0.1mm). So, use a gauge with 0.1mm resolution and save the effort of recording/rounding one digit of noise. ;)

The extra digit probably looks cool in your spreadsheets, though.
I'm not really interested in tread depth to a high resolution. I'm more interested in tread wear to a high resolution. For that, taking two measurements per channel in the same places every time gives me better wear data. Those digital gauges are a modification of a machinist's depth gauge, and are amazingly accurate. I do have to zero it before use, but that's no more than 0.002". Similarly, my $70 Seiko digital stopwatch is more accurate than a $5000 Rolex.

I record the full displayed depths in my raw data, but for my "reported" data used to make decisions I only worry about 0.01/32" All my rounding and averaging is automatic, no effort required. Since the first digit in wear data is usually a "1' when reported in 1/32", carrying that next digit is useful.

The important data is in blue font: inside channel wear vs. outside channel wear (assessing alignment) and average side channel wear vs. average middle channel wear (assessing inflation pressure).

Product Rectangle Slope Font Line


My inside channel wear vs. outside channels wear is all over the place, but the four-tire average is about where it needs to be (0.10/32"). The scatter is averaged out and pretty much cancelled with tire rotation. I'm not sure another alignment would improve tire life. Back at the 17k mile tire rotation, the average was 0.27/32" more outside channel wear than inside channel wear. That caused me to get an alignment. For the next two rotation stints, the average outside channel wear was 0.09/32" and 0.10/32". So, the alignment was necessary and effective.

At 29k miles, the average outside channel depths is about 0.5/32" less than the inside channel depths. These tires are symmetric. So, instead of getting another alignment I'm going to have the tires flipped on the rims. That should result in the inside and outside channel depths being just about identical at the end of the tires' life (60k to 70k miles).

I'll get to 50k or 55k miles and still have a minimum of 4/32" of depth in each channel. For those leasing their BMW, that would avoid an "excess tire wear fee" at lease turn in. My service writer at BMW of Bubbaville asked me to please not tell other customers that I'm getting 60k to 70k miles out of my tires. She said they'll be pissed... at her.

For the current rotation stint, I've increased the tire pressures from 39 PSI to 40 PSI. These tires, Bridgestone Duelers, came with 1/32" more depth in the middle channels. So, concentrating wear in the middle channels with increased pressure will extend the life of the tires. With sufficient resolution of my calculated wear data, I'll be able to see if the extra one PSI makes a difference.

My top nine records for a set of tires are: 79k miles, 74k miles, 70k miles, 70k miles, 68k miles, 65k miles, 60k miles, 60k miles, and 55k miles. The tenth set of tires only got 46k miles, but that's because Frau Putzer shredded them causing large chunks to tear off the tread blocks. She drives like a chimpanzee on crack.

This whole "Tire Whispering" thing is one of my many "outcome manipulation games," and I'm winning.
 

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A common Problem with measuring tools is "too much precision".

Try finding a reasonably priced digital calipers that reads out ¹/₆₄ inch not ¹/₁₂₈.

64th's are small enough to be useful and big enough to snap in to a reliable number. 128th's from a practical point are about add useless as a "chain" (66 ft FYI) for everyday measuring.

I use my 1/64 dig caliper for tire meausure but I'm going to get an analog dial gauge that reads in 32s but has makings for 128th.

GODESON Tire Tread Depth Gauge, Dial Type Tire Tread Depth Gauge Professional for Motorcycle, car,Truck and Bus,Easy Reading Tire Tread Depth Gauge in 32nds


 

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A common Problem with measuring tools is "too much precision".

Try finding a reasonably priced digital calipers that reads out ¹/₆₄ inch not ¹/₁₂₈.

64th's are small enough to be useful and big enough to snap in to a reliable number. 128th's from a practical point are about add useless as a "chain" (66 ft FYI) for everyday measuring.

I use my 1/64 dig caliper for tire meausure but I'm going to get an analog dial gauge that reads in 32s but has makings for 128th.

GODESON Tire Tread Depth Gauge, Dial Type Tire Tread Depth Gauge Professional for Motorcycle, car,Truck and Bus,Easy Reading Tire Tread Depth Gauge in 32nds

I used to use a mechanical tread depth gauge with 1/32" markings. I could eyeball it to maybe 1/64" or 1/128". When computing wear (not depth), that wasn't enough resolution.

There's no such thing as too much accuracy or resolution when collecting raw data. For analysis, yeah, it's important to know what's useful and not useful.
 

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3er + 3er + 4er = 10er, Bimmers?!
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Similarly, my $70 Seiko digital stopwatch is more accurate than a $5000 Rolex.
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.
 

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Discussion Starter · #38 ·
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.
 
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