BMW OEM Style 296 Wheel POLL

[Mr. ///M3 RD]

You may have read in this or other forums that Z4 drivers with OEM Style 296 wheels have experienced wheel cracks.

This is a multiple choice poll we like to find out how many of you have Style 296 wheels, what tire you been running, are you inspecting your wheels and if you had any wheel cracks.

If the poll does not meet your needs do leave a post with more details.

Remember the most important part between you and the road are your wheels.

Thanks,

Rolf-Dieter

[HerrK]

8000+ miles, stock RFT's, L&R rear replaced at 4&7 K due to punctures, thorough visual inspect wheels @ 5K, cursory look every other week or so when I wipe down the wheels, hit ocassional potholes yes, try to avoid potholes yes, Oct 2010 date of wheel mfg, daily driver.

[Kief]

2009 Z435i w/#296 rims and original RFT:
4k+/- miles on #296 (6k+ on car).
Tires/psi checked weekly; rims wiped down daily (if driven and weather permitting).
Inside of rims cleaned and inspected once a year after winter set-up has been installed.

[MikeChrista]

Rolf - Thanks for setting up the poll. I have 296 and RFT. I inspect regularly (after the initial info about cracks) and have not seen any yet! Car was purchased in Sept 09 and has done just under 10000 miles. I have hit a few potholes and most driving has been in UK with a couple of longer (and faster!) trips to Germany.

[Constant.S]

The cracks most probably will be in the inner lip of the wheel, thats what happened with me, i cut one of my Michelin PS2 and in the process of changing it i found a large crack on the rear wheel. The process of fixing it tho was easy and relatively cheap, but since then i check the tire pressure regularly since its the only way of telling there is a non visible crack.

[Mr. ///M3 RD]

Originally Posted by Constant.S

The cracks most probably will be in the inner lip of the wheel, thats what happened with me, i cut ony of my Michelin PS2 and in the process of changing it i found a large crack on the rear wheel. The process of fixing it tho was easy and relatively cheap, but since then i check the tire pressure regularly since its the only way of telling there is a non visible crack.

You are wise to check the air pressure on a regular basis (I check mine every week). Low air pressure with the 2.5 degree camber on your rear wheel will transfer even more forces/stress to the inner outer rim (where the cracks appear).

I would not recommend repairing cracks, however, you are checking your wheel often and that is a good thing.

I assume by inner lip you mean the area were you see the crack in the picture below, this is were the cracks apear (photo from my photo album).

[zEdP]

After 17500 miles, everything is still ok, based on the air pressure.

I'm a little bit worried to be a 296 'crack victim' too. I travel a lot on Belgium roads that are very bad. I contacted BMW with a question about the warranty on cracked wheels. They want to check a damaged wheel first to determine if the warranty can be claimed. I don’t have a damage wheel and I want to keep it that way.

If you are cautious driver and just unlucky to get 'cracked' after 3 years / 30000 miles, the wheel damaged should be covered by warranty. Because there reasonable assumption that wheels are not worn out within 30000 miles. But it's hard to prove you’re careful driver.

End of this year I will definitely switch to non RFTs, it is a shame to replace also the front tires that are still in perfect conditions. But switching to the non RFT will extend the life of my 296's.

[Mr. ///M3 RD]

Originally Posted by zEdP

After 17500 miles, everything is still ok, based on the air pressure.

I'm a little bit worried to be a 296 'crack victim' too. I travel a lot on Belgium roads that are very bad. I contacted BMW with a question about the warranty on cracked wheels. They want to check a damaged wheel first to determine if the warranty can be claimed. I don’t have a damage wheel and I want to keep it that way.

If you are cautious driver and just unlucky to get 'cracked' after 3 years / 30000 miles, the wheel damaged should be covered by warranty. Because there reasonable assumption that wheels are not worn out with 30000 miles. But it hard to prove you’re careful driver.

End of this year I will definitely switch to non RFTs, it is a shame to replace also the front tires that are still in perfect conditions.

Just inspect your wheels on a regular basis. When you detect a hairline crack bring the car back to BMW and demand a replacement. If the crack opens up it will no longer pass the BMW "Out off Round" inspection. The BMW TIR (Total Indicator Reading) is 3 mm that is 0.012"

We all try to avoid potholes, I am a very careful driver and still after 18,000 KM I lost 2 rear wheels. In my humble opinion I blame the camber angle (2.5 degree on our Z4 cars) and the stiff sidewall of the RFT. This is why I have taken one item out off the equation namely I eliminated the RFT.

Also, do not neglect to check your tire pressure often (I check it weekly).

[zEdP]

Originally Posted by Rolf-Dieter

Just inspect your wheels on a regular basis. When you detect a hairline crack bring the car back to BMW and demand a replacement.

Rolf-Dieter, you only check the rear tire pressure?

How fast does the pressure drop within a day or week if there is a hairline crack? I guess it will drop fast even with a hairline crack.

[Mr. ///M3 RD]

Originally Posted by zEdP

Rolf-Dieter, you only check the rear tire pressure?
How fast does the pressure drop within a day or week if there is a crack?

No I check all 4 wheels for pressure. I cannot answer your second question in my case the TPMS gave me an alarm after I started my car (after parking her for 2 hours). I was close to a gas station, topped up the pressure and drove to my hotel. In the morning in the hotel garage the TPMS again alarmed, I drove to a tire shop about 1/2 mile they found the crack.

[Frank Costanza]

I'm going to crawl under our car in the morning with a flash light and take a look.

[Mr. ///M3 RD]

Originally Posted by Frank Costanza

I'm going to crawl under our car in the morning with a flash light and take a look.

Frank, Please do this in a safe way, crawling under the car is not an option, as you know there is not sufficient room to do this.

Remove the wheel (block your car while the wheel is out for safety), clean and inspect it under good light ....

or

Drive into a service bay pay someone to lift your car clean your wheels on the inside then inspect for cracks using a good light.

Safety first !

Take care.

Rolf-Dieter

[Constant.S]

Originally Posted by Rolf-Dieter

I assume by inner lip you mean the area were you see the crack in the picture below, this is were the cracks apear (photo from my photo album).

Exactly! Thats where mine cracked.

[MikeChrista]

Interesting that currently we only have 16.6% with cracks from this poll and 1 (Rolf) was primarily in the USA, Constant S profile says Greece/Canada and I am not sure about Shiro. Would be interesting to know a bit more about the driving habit of Constant and Shiro - I think we all have Rolf's details

[zEdP]

Hi,

I have joined the 296 inspection club.
From now on I will check once a week the pressure of all 4 tires.

[Mr. ///M3 RD]

Originally Posted by MikeChrista

Interesting that currently we only have 16.6% with cracks from this poll and 1 (Rolf) was primarily in the USA, Constant S profile says Greece/Canada and I am not sure about Shiro. Would be interesting to know a bit more about the driving habit of Constant and Shiro - I think we all have Rolf's details

Yes my details are well documented

... as for the percentage of cracks, I only voted once, however, I had three (3) cracks. one (1) in the rear driver side and two (2) in the rear passenger side. I'm sure there are many more out there that don't know about our forum and just pay the bill and take it as a normal situation or believe the SA when he tells them "Sorry you went thru a pothole, here is your invoice that be $700- please"

[Mr. ///M3 RD]

Originally Posted by zEdP

Hi,

I have joined the 296 inspection club.
From now on I will check once a week the pressure of all 4 tires.

Good plan, since with RFT our eyes are useless only the pressure gauge will tell the truth (provided it is a good one )

[++Tatoz++]

Got my Z4 35is yesterday with stock 296 rims.

While I was waiting for the delivery I met a guy who has a 35i and have experienced 3 (three) cracks with 296 rims. He said all the cracks were under warranty but still the dealer hasn't offered any rim change.
I then asked the sales rep any explanation and how BMW in Italy is handling the issue, the rep said no actions have been taken by BMW but it is very uncommon to see defective 296 rim and blamed the other customer for a non responsible driving behavior which raised my concerns to an higher level.

Today I drove about 200 careful miles, will report back in something happens.

[Mr. ///M3 RD]

Originally Posted by ++Tatoz++

Got my Z4 35is yesterday with stock 296 rims.

While I was waiting for the delivery I met a guy who has a 35i and have experienced 3 (three) cracks with 296 rims. He said all the cracks were under warranty but still the dealer hasn't offered any rim change.
I then asked the sales rep any explanation and how BMW in Italy is handling the issue, the rep said no actions have been taken by BMW but it is very uncommon to see defective 296 rim and blamed the other customer for a non responsible driving behavior which raised my concerns to an higher level.

Today I drove about 200 careful miles, will report back in something happens.

The dealer statement non responsible driving behaviour is a ton of BULL!

They are trying to pull the wool over peoples eyes. Compare the spokes on the 296 wheel design to other wheels and you will quickly see that the 296 spokes do not provide much support to the wheel (compared to other wheels).

I just added a Page 9 to my link below with some Recommendations.

[++Tatoz++]

Rolf, thanks for sharing your story, I went through it this morning with my cup of coffee as suggested.
It is very valuable information the one you've provided and keep providing, I'll keep checking both wheels and your threads.

I also enjoyed your driving style and passion, reading about your journeys made me jealous, although I live in Italy I do travel a lot in the US (Canada is still in the plans) and I'm actually right back after a glorious ride on the PCH from LA to San Francisco, you can see my memory of the trip here:

The trip was supposed to be ridden on a new Z4 but the car rental failed to provide me the car so I opted for the SLK, one more reason to drive the PCH again in 2012.......

[HerrK]

Originally Posted by Rolf-Dieter

Compare the spokes on the 296 wheel design to other wheels and you will quickly see that the 296 spokes do not provide much support to the wheel (compared to other wheels).

Rolf,

I have to respectfully disagree with your correlation between cracks on the inboard side of the rim and the support structure @ the outboard edge. If the cracks were propogating at the outbard edge, that theory might hold water. The funtion of the spokes, beside to support the tire/rim are mainly transmitting the rotational forces of the brakes or engine to the rim/tire. Since the inboard side of the rim is so 8-9" from the spokes the OD of the rim at the inboard edge must provide support/structural integrity alone.

[Mr. ///M3 RD]

Originally Posted by HerrK

Rolf,

I have to respectfully disagree with your correlation between cracks on the inboard side of the rim and the support structure @ the outboard edge. If the cracks were propogating at the outbard edge, that theory might hold water. The funtion of the spokes, beside to support the tire/rim are mainly transmitting the rotational forces of the brakes or engine to the rim/tire. Since the inboard side of the rim is so 8-9" from the spokes the OD of the rim at the inboard edge must provide support/structural integrity alone.

HerrK,

I respect your opinion and welcome them. However, we are all entitled to our own opinion. Many a times have probable causes of failures been discussed in my long involvement in the field of engineering. I have experienced the failures first hand and seen the two different cracks (the open one as shown in the photos) and the 2 hairline cracks in my passenger side rear wheel. The wheel that made my home drive of over 3,000 KM not exactly a ride of joy if you know what I mean.

You may have overlooked what I said in my posts of having driven thru the Mohave desert with a passenger (my daughter) and the top in the trunk (she so enjoyed the top down drive). At one point we stopped at a rest stop the sign told us we were 6 feet above sea level (perhaps you been there). Anyway the temperature was 120 F I happen to touch my wheels they were so hot I could not keep my hand on the tires nor the wheel.

You speak about crack propagation. You may have noticed how the crack in the attached picture is propagating from the inner outer rim toward the outer wheel rim having the stronger wheel area namely the spokes.

I think we can agree on the following points;

A) The weaker side of the wheel is the inner outer rim.
B) The spokes are not exactly the strongest I've seen.
C) The brakes on our car have no cooling holes.
D) The wheel (on the inside) takes the highest load with the RFT and camber
E) The RFT with the stiff steel sheet enforced side wall must be transmitting a great deal of forces onto the inner outer rim of the wheel.
F) Why I wonder is Bridgestone redesigning the RFT again and again now at Generation III with cooling fins on the sidewalls.
G) Why are there no cooling holes in our brakes (even my new MB C350 4MATIC has cooling holes in the breaks - see photo below).

And the list goes on and on. I don't know exactly where the crack(s) started, I know this that they all start in the same area namely on the outer diameter of the inner wheel rim. Now if they start at the very tip or base or at the face no one really knows. I do know they start as a hairline crack and propagate in a transverse direction in line with the axel. The hairline crack then opens up to continued radial forces and load until the point that you loose air pressure.

Whatever the root cause be it one ore more of the listed items of concern above or may it be poor casting quality or defective material. All this is besides the point. The end result could be someone looses his life a good example is the post by ghani titled RFT !?!?!?!? How many more 296 wheel cracks must there be before something is done?

As I said it is a safety issue, I always (like most) treat safety as number 1.

Once I get my wheel back perhaps I will cut samples and go ahead with a full blown non-destructive testing program, material analysis including finite analysis. Time will tell what I will do, after all I am retired and I have time on my hands. As they say, keep active