The BMW E28 Wheel and Tire Tutorial: Difference between revisions

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<center></center>As with most any vehicle, one of the easiest ways to change the look and performance of an E28 is by changing the wheels and tires, and this tutorial is geared to helping you find a setup that fits properly.  Considering the range of opinion with regard to appearance, performance goals, driving environment, and one's financial wherewithal, trying to determine which setup is "best" is rather subjective and won't be discussed here.
''By [https://www.mye28.com/memberlist.php?mode=viewprofile&u=6419 Shawn D.]''
 
As with most any vehicle, one of the easiest ways to change the look and performance of an E28 is by changing the wheels and tires, and this tutorial is geared to helping you find a setup that fits properly.  Considering the range of opinion with regard to appearance, performance goals, driving environment, and one's financial wherewithal, trying to determine which setup is "best" is rather subjective and won't be discussed here.


The subject of wheels and tires is actually less complicated than it often seems to be, and this tutorial should clear up almost any question you might have about properly fitting wheels and tires to an E28.  However, this tutorial isn't intended to be a complete A-to-Z education on the subject of wheels and tires.  For that, visit a library, use Google, and check out Tire Rack's excellent wheel tech and tire tech sections.
The subject of wheels and tires is actually less complicated than it often seems to be, and this tutorial should clear up almost any question you might have about properly fitting wheels and tires to an E28.  However, this tutorial isn't intended to be a complete A-to-Z education on the subject of wheels and tires.  For that, visit a library, use Google, and check out Tire Rack's excellent wheel tech and tire tech sections.


'''Stock Wheel and Tire Sizes'''
=== '''Stock Wheel and Tire Sizes''' ===
 
US-spec E28s were fitted with the following wheel and tire combinations...
US-spec E28s were fitted with the following wheel and tire combinations...
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Fitment:  Will fit all E28s running stock brakes or the common E32/E34 "Big Brake Upgrade."  Non-M5 E28s might encounter rear fender lip interference with this setup (more on this in the "Fender Rolling or Trimming" section below); M5 rear fender lips are pre-trimmed by the factory.
Fitment:  Will fit all E28s running stock brakes or the common E32/E34 "Big Brake Upgrade."  Non-M5 E28s might encounter rear fender lip interference with this setup (more on this in the "Fender Rolling or Trimming" section below); M5 rear fender lips are pre-trimmed by the factory.
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'''Stock Wheels with Non-Stock Tire Sizes'''


=== '''Stock Wheels with Non-Stock Tire Sizes''' ===
There are a few options if you want to run non-stock tire sizes on stock E28 wheels...
There are a few options if you want to run non-stock tire sizes on stock E28 wheels...
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|The speedometer reading will be unaffected, but rear fender lip interference is possible.  Due to the aforementioned obsolescence of the TRX design, this is ''not'' considered an "upgrade."
|The speedometer reading will be unaffected, but rear fender lip interference is possible.  Due to the aforementioned obsolescence of the TRX design, this is ''not'' considered an "upgrade."
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'''Bolt Circle, Lug Size, and Hub Diameter'''


=== '''Bolt Circle, Lug Size, and Hub Diameter''' ===
E28 wheels have a bolt circle of 5x120mm, with lug bolts that thread into the hub, as opposed to fixed studs onto which lug nuts are threaded.  The bolts themselves have a 12x1.5mm thread size, with a proper torque of 75ft-lbs.  E28 wheels are hubcentric, with a hub diameter of 72.5mm.  Note that while the standard GM bolt circle of 5x4-3/4" (5x120.65mm) is ''very'' close, GM wheels are not suitable for use on an E28, except in an emergency.
E28 wheels have a bolt circle of 5x120mm, with lug bolts that thread into the hub, as opposed to fixed studs onto which lug nuts are threaded.  The bolts themselves have a 12x1.5mm thread size, with a proper torque of 75ft-lbs.  E28 wheels are hubcentric, with a hub diameter of 72.5mm.  Note that while the standard GM bolt circle of 5x4-3/4" (5x120.65mm) is ''very'' close, GM wheels are not suitable for use on an E28, except in an emergency.


'''List of Known Wheel and Tire Combinations'''
=== '''List of Known Wheel and Tire Combinations''' ===
 
The majority of wheel and tire combinations known to fit the E28 can be found in the '''E28 Wheel & Tire Database'''. It's important to understand that the database is ''inclusive'', in that all of the combinations listed have been proven to fit.  It is not ''exclusive'', meaning that the listed combinations are not all that could possibly fit.
The majority of wheel and tire combinations known to fit the E28 can be found in the '''E28 Wheel & Tire Database'''. It's important to understand that the database is ''inclusive'', in that all of the combinations listed have been proven to fit.  It is not ''exclusive'', meaning that the listed combinations are not all that could possibly fit.
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|Values which are used in the calculations in the "E28 Wheels & Tires" sheet.
|Values which are used in the calculations in the "E28 Wheels & Tires" sheet.
|}
|}
'''Download the E28 Wheel & Tire Database in MS Excel format here''' (right-click and select the "save" option).  This file is a zipped MS Excel spreadsheet; for questions or problems regarding .zip files, refer to Winzip's "Basic Information" and FAQ pages.
'''[https://wiki.mye28.com/images/6/6f/Wheels-Tires_E28_2012-01-04.xls Download the E28 Wheel & Tire Database in MS Excel format here]'''.  This file is a MS Excel spreadsheet.
 
For those without Excel, you can view the E28 Wheel & Tire Database in table format.  This table doesn't have the functionality of the spreadsheet (user inputs, calculations, variables, etc.), but it can be viewed by anyone with a browser.  Note that this version contains only the list of wheel & tire combinations.
 
'''Spacer and Hub Bore Adaptor Usage'''


=== '''Spacer and Hub Bore Adaptor Usage''' ===
Some of the wheel and tire combinations listed in the E28 Wheel & Tire Database will require the use of spacers or hub bore adaptors.
Some of the wheel and tire combinations listed in the E28 Wheel & Tire Database will require the use of spacers or hub bore adaptors.


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E39 wheels have a hub diameter of 74mm, which is too large for the E28's 72.5mm.  Thus, to properly fit them to an E28 and maintain hubcentricity, a hub bore adaptor ring is necessary.  The adaptor ring doesn't change the relative position of the wheel to the hub, but ensures hubcentricity by taking up the 0.75mm gap between the E39 wheel and the E28 hub.  Not using these adaptor rings can result in an imbalance/vibration condition similar to that of an out-of-round wheel and tire assembly.  These adaptors can be purchased from Tire Rack, among others.
E39 wheels have a hub diameter of 74mm, which is too large for the E28's 72.5mm.  Thus, to properly fit them to an E28 and maintain hubcentricity, a hub bore adaptor ring is necessary.  The adaptor ring doesn't change the relative position of the wheel to the hub, but ensures hubcentricity by taking up the 0.75mm gap between the E39 wheel and the E28 hub.  Not using these adaptor rings can result in an imbalance/vibration condition similar to that of an out-of-round wheel and tire assembly.  These adaptors can be purchased from Tire Rack, among others.


'''Fender Rolling or Trimming'''
=== '''Fender Rolling or Trimming''' ===
 
Many wheel & tire combinations will require minor modification of the rear fender lip due to tire-to-fender interference.  There are two methods:  "rolling" and "trimming"...
Many wheel & tire combinations will require minor modification of the rear fender lip due to tire-to-fender interference.  There are two methods:  "rolling" and "trimming"...
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|Trimming
|Trimming
|A Dremel or die grinder with an abrasive cutoff wheel is used to remove a slice of the inner fender lip at the interference point.
|A Dremel or die grinder with an abrasive cutoff wheel is used to remove a slice of the inner fender lip at the interference point.
See this diagram for more information on this technique.
[https://i.imgur.com/s7WpCW2.jpg See this diagram for more information on this technique.]
|Pros:  Maintains fender lip profile.  The more precise of the two methods.  Does not crack paint or undercoating, and does not leave a grit-attracting pinched channel.  Easy to touch up raw edges with paint or undercoating.
|Pros:  Maintains fender lip profile.  The more precise of the two methods.  Does not crack paint or undercoating, and does not leave a grit-attracting pinched channel.  Easy to touch up raw edges with paint or undercoating.
Cons:  Takes more time.  Can burn paint close to cut and affect temper of the metal if not done carefully.  Slightly reduced fender lip strength.
Cons:  Takes more time.  Can burn paint close to cut and affect temper of the metal if not done carefully.  Slightly reduced fender lip strength.
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'''Still Have Questions?'''


=== '''Still Have Questions?''' ===
If, ''after'' thoroughly reviewing the info on this page, you have questions on wheels and tires for your E28, feel free to ask questions in the '''MyE28.com Forums'''!
If, ''after'' thoroughly reviewing the info on this page, you have questions on wheels and tires for your E28, feel free to ask questions in the '''MyE28.com Forums'''!
 
[[Category:Tech FAQ]]
-Shawn D.
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