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      11-01-2020, 10:10 AM   #1
hjulicher
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Help Needed: Incorrect tire size installed by dealer

Dear Bimmerpost Community,

This is my first post on this thread after coming here to learn more about my F31. I bought the car a year ago in November and well I have had my share of questions and issues.

I'm having a bit of trouble with the dealer and need your expertise/advise.

I bought my car used from Erhard BMW of Bloomfield Hills (Metro Detroit). The car came with 2 sets of wheels. At time of purchase, only the double spoke 18" 398 wheel in grey/black was installed on the car with summer performance tires.

As it had already snowed in Michigan, the dealer showed me a pic of the winter rims which were part of the deal (the standard M441 double spoke rim). Unfortunately, at time of delivery they told me that there were mistaken when the showed me the picture and that I would be getting the BMW 393 single spoke rim in 17". As these rims were for winter use, I didn't bother the fight as the rims were cosmetically in perfect condition.

With the 17" wheel the dealer installed new winter Michelin X-Ice Tires. They installed however 225 45R17 tires. I didn't bother to check whether this was correct size or not as I didn't expect this to be incorrect.

A year has now passed and after putting on the winter tires looking to find the correct tire pressure to fill the 17" rim, I noticed that the 17in tires should be 225 50R17. Basically, the tires installed by Erhard were smaller than prescribed.

This had several a-ha moments for me as I now understood why Waze was showing such a large discrepancy in speed vs the speedometer (>6mph) and why my fuel economy was several MPGs better with the winter tires than on the summer performance tires.

My questions:
- Is there any way to find out what would have been the factory delivered wheels with the car based on VIN?
- Is ok that the winter tires are not offset front/back as the summer tires?
- What implications other than incorrect speed and odometer would smaller tires have?
- What is the difference between the two sizes in terms of calibration. Is 1 mile on the correct wheel size the equivalent of 1.06 miles on the incorrect smaller size?
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      11-01-2020, 11:19 AM   #2
alohasurftoad
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the difference is 3.6% between the two. so you are accruing 360 more miles every 10000 miles with the smaller diameter. you can also think of it like you're being "shorted" mileage. every 10000 on the odometer = 9640 true

you acceleration should be improved due to "shorter" gearing at the pavement
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      11-01-2020, 02:49 PM   #3
Shred Sled
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My 2016 F31 328ix came with 398 (225/45 R18 Front / 255/40 R18 Rear)

For snow tires, I'm running 405M (225/45 R18) all around.

Square is what I believe most use for snow tires. While the circumference is different as AlohaSurfToad mentioned, it looks as though the section width is the same (thinner tire usually preferred). Your current winter tire has more sidewall which may provide better better protection on winter beaten roads (ex potholes)
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      11-02-2020, 06:25 AM   #4
hjulicher
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Im sorry but what is square? Never heard of that

Anyways Iím sure that the 393 wheel was not standard on any model in the 2017 MY. Also the rims are 17Ē so the sidewall should be 50, which is fine for Michigan roads in the winter. Im just amazed at the dealer unprofessionalism by a) trying to swindle me out of the standard rims, b) putting the wrong size on the car for whatever reason.

Iíve contacted the sales team and Iím waiting to see how they will respond.

Erhard also failed to give me the jack, fix-a-flat kit and a wrench to even change a tire. I had to get these from a friend whoís Audi A4 was totalled.
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      11-02-2020, 08:52 AM   #5
clemsonf31
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Quote:
Originally Posted by hjulicher View Post
Im sorry but what is square? Never heard of that

Anyways Iím sure that the 393 wheel was not standard on any model in the 2017 MY. Also the rims are 17Ē so the sidewall should be 50, which is fine for Michigan roads in the winter. Im just amazed at the dealer unprofessionalism by a) trying to swindle me out of the standard rims, b) putting the wrong size on the car for whatever reason.

Iíve contacted the sales team and Iím waiting to see how they will respond.

Erhard also failed to give me the jack, fix-a-flat kit and a wrench to even change a tire. I had to get these from a friend whoís Audi A4 was totalled.
Square means same wheel size/width front and rear; as opposed to staggered which may have wider rear wheels. Additionally, from my experience, these vehicles donít come with a jack as they come standard with run-flat tires. Thus there is Ďno needí for such items

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      11-02-2020, 09:08 AM   #6
pr0gi
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It shouldn't be a big deal. Just the car might sit a bit lower. This tyre size is for 18" wheels. It is strange however that 17" are with this size of tyres because usually from what I know wheels and tyres come together from factory so it is either factory mistake or dealer made some last minute changes.
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