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2016 M235i run flat tires

2K views 15 replies 6 participants last post by  Zooks527 
#1 ·
Front: Michelin Pilot Super Sport 225/40R18 (run flat) @ 32 psi
Rear: Michelin Pilot Super Sport 245/35R18 (run flat) @ 38 psi

I am constantly losing pressure in these tires, refilling, and resetting the Tire Pressure Monitor. Every 3 to 4 weeks.
Always a different tire but rears more often. I see no reason for this.
Is this symptomatic of 'run flats'?
Any one else have this problem?
 
#2 · (Edited)
I'm pretty sure those are non-run-flats. Michelin makes run-flat PSS's, but not in those sizes.

Tires will leak down over time. Mine leak somewhere between a half-PSI and one PSI every two to three weeks. An embedded nail or screw will cause them to leak down faster. Tire pressure goes up or down about one PSI for every ten degrees F.

Get a quality tire gauge. Meiser is the industry standard. They've about $30.

A quality hand pump is less hassle than fighting with extension cords for electric pumps. Topeak makes good pumps under their "Joe Blow" brand. Their mountain bike pump is a high-volume, low-pressure (for a bicycle) pump with a rated pressure of 75 PSI. They're about $70. That's enough to pump up a donut spare on a car.

Let the car cool off overnight. If you have a garage, it helps to open the hood, too. BMWs' engine compartments get so hot and are sealed up so tight that they still heat the front tires after twelve hours. Before sunlight hits the tires and heats some them up, check and adjust the pressures. Adjust both tires on each axle to have exactly the same pressures. Record the data: date, temperature, mileage, and pressures for each tire. Reset the TPMS.

Do the steps above in a week or two, probably after just one week if you suspect something is wrong. If the tire pressures are different on an axle, you probably have at least one embedded nail or screw. Over the decades, I've caught literally dozens of slow leaks caused by punctures this way. I've caught them early enough that I can deal with them in a convenient place and at a convenient time. Attached is a screenshot from my maintenance logbook showing how I caught a puncture early. The right-rear had lost about a fourth-PSI. I looked for, but couldn't find an embedded nail or screw. I assumed I might have mis-measured the pressure by a fourth PSI. The next time, it'd lost about a half-PSI. I removed the wheel to look for a puncture, and... Whomp! There is was!

You're much more likely to get a puncture on the back. A screw or nail laying on its side in the road is not much of a threat. But, the front tire runs over it and causes it to start tumbling down the road. If the back tire then hits it when it's anywhere near upright, you're... well... nailed, or screwed.

The proper way to repair a puncture is to remove the tire and install a "plug-patch system." It's important that the shop has a lever-less tire machine that does not touch (and scratch) the outside of your rims. A tire puncture is repairable if it's not in the outer or inner section of tread.

Think about a spare tire and a jack, since you now know you don't really have run-flats. Bimmerzone.com sells them. Actually, if you take road trips in your car you need a spare even with run-flats.
 

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#3 ·
Autoputzer - thanks for the thoughtful reply. However ....
Those are my exact tires as written on the sidewalls.
Mine leak more often than yours.
No nail or screw puncture as different tires leak down at different rates but no one consistently low. I keep a log now.
My compressor hose can reach all the tires. More effortless for me than a hand pump.
Tires always checked when cold. TPM always reset.
I absolutely have run flat tires. Verified by Michelin and old expert at tire shop.
As soon as I have enough wear, I will switch to regular tires.
 
#5 · (Edited)
Those extensions open the OE valve. So, you're now depending on your aftermarket valve stem extensions to hold the air in.

Do your tires say "ZP" on them? That's what I've seen on Michelin run-flats, standing for "zero pressure."

A friend of mine has a F83 M4, and swears he has run-flats. But I could never find "ZP," "RFT," "RUN FLAT," or anything else on the sidewalls. He called the BMW dealer, put his phone on speaker, asked the service writer if he had run-flats. The service writer said "yes." So, then my friend was pissed at me. I punched his car into Tire Rack's tire selector, and the BMW OE PSS's came up and didn't say anything about being run-flats. So, then he was even more pissed at me... because the service writer said he had run-flats... the same service writer who said he had to buy a new tire to replace his punctured tire ($400+) instead of patching it ($30)... because it was a run-flat.
 
#6 · (Edited)

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#7 · (Edited)
I have some valve stem extensions in my tool box, and went to look at them tonight. I used them to get to short valve stems on the old Honda Frau Putzer brought to the marriage. They wouldn't normally open the valve when installed. But, when some unusual adverse event occurs, the normal fault isolation process is to look first at the unusual existing conditions. I'd remove those extensions before starting to track pressure losses.

There's a technique to using a tire pressure gauge without losing pressure out of the tire. The gauge head needs to contact the valve with the exact same orientation. That's easy with a dial gauge that has an extension hose (as shown in Post #2). Also, if you're using a pencil gauge, all bets are off. Throw that thing away.
 
#9 · (Edited)
Nope. They wanted $400 from you for a new tire, instead of $25 to install a plug-patch.

RFT's can't be patched if they've been driven on with no air pressure, or if the puncture is near the edge of the tread (as shown above). Running a RFT with zero pressure weakens the reinforced sidewalls.

Check your tire warranty (in the owner's manual pouch). You might have been due a new tire, or only should have paid the pro-rated cost of a new tire.

http://www.pirelli.com/mediaObject/...FlatWarranty/original/002-RunFlatWarranty.pdf

Oops! Hawaii... Make that $500 for a new tire.
 
#12 ·
OP, check the valve stem nuts to make sure they are fastened properly. My previous F30 had an unexplainable slow leak in one tire with no nail or puncture visible. It would go down about 1-2 psi per week. At the next service, I told the SA about it and the mechanic found the lock nut was not tightened completely. No issues after that.
 
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