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      03-26-2023, 09:24 AM   #1
2007z4blue
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7.5 Wheel Size

Want to switch out my black wheels that came w/ my Z4 for some OEM silver wheels off a 3 Series. The wheels have a similar offset and came stock with the same size tires that came on my Z ( 225/45/17s ). The issue is they are 7.5 inches wide and mine are the 8 inche size as was factory spec for my model.

If I don't plan on switching to larger tires, will the 7.5 inch wheel matter? As I said, they came from the factory with the same exact tire setup I'm running.
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      03-26-2023, 09:35 AM   #2
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Quote:
Originally Posted by 2007z4blue View Post
Want to switch out my black wheels that came w/ my Z4 for some OEM silver wheels off a 3 Series. The wheels have a similar offset and came stock with the same size tires that came on my Z ( 225/45/17s ). The issue is they are 7.5 inches wide and mine are the 8 inche size as was factory spec for my model.

If I don't plan on switching to larger tires, will the 7.5 inch wheel matter? As I said, they came from the factory with the same exact tire setup I'm running.
If the 7.5 and 8 wide are the same offset the 7.5 will tuck in .5” more. 225 is the widest you can put on a 7 wide rim so you’ll be fine tire size but might look bit odd tucked in that much unless using spacers. The stock 16x7 had offset off 47. Use https://www.1010tires.com/Tools/Wheel-Offset-Calculator
to see the differences in sizes and offsets you’re looking at.

Last edited by Piper1; 03-26-2023 at 09:50 AM..
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      03-26-2023, 10:27 AM   #3
2007z4blue
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Thank you Piper for the info. That puts a damper on my idea, as a more inward wheel stance would not be what I want.

The only other 17 inch BMW wheels I've found locally have a 12mm difference in offset (34mm). I love the wheels but have seen no info on whether that can work-or is even safe?
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      03-27-2023, 07:53 PM   #4
2007z4blue
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Ok- If I only look at 8.0 inch wide wheels, any suggestions how far from the stock can I safely go regarding offset? My understanding is that I have 47mm of offset all around. I want to possibly switch wheels to some 3 Series rims that have 34mm of offset. I will be running the stock tire setup -225/45/17. Is this an unsafe practice? It doesn't look as though anything would rub. Thanks for any thoughts.
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      03-27-2023, 11:46 PM   #5
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Quote:
Originally Posted by 2007z4blue View Post
Ok- If I only look at 8.0 inch wide wheels, any suggestions how far from the stock can I safely go regarding offset? My understanding is that I have 47mm of offset all around. I want to possibly switch wheels to some 3 Series rims that have 34mm of offset. I will be running the stock tire setup -225/45/17. Is this an unsafe practice? It doesn't look as though anything would rub. Thanks for any thoughts.
Max rear would be around et22 max front around et28-30 at 8”width. When I ran my stock turbines 8”wide et47 I added a 25mm spacer rear 15mm front with I think a 235/40/17. Think max spacer I’ve seen without rolling fenders and adding neg camber on the front would be 20mm front spacer 30mm rear but I think that’s playing with fire if you’re stock suspension with little adjustment, maybe pull the alignment pins on the front to help if you’re trying to go the farthest you can out. et34 extends 13mm out from where you are now so very safe on 225/45/17

Take a good ole ruler and measure from the outer on your tire to see just where you’d like to sit and plug in your info to the 1010 site linked there to calculate for your offset you’d want to hit at per your ruler measurement.
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      03-30-2023, 07:10 AM   #6
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Thanks Piper for the great info. I think I'm gonna pull the trigger on those 3Series wheels. I'll post some before/after pics.
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