01-10-2020, 05:05 PM | #1 |
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Tire question for 668M wheels
I am thinking of getting the M550i to replace my A6. Love the 20 inch 668M wheels (and do not really like the 19s).
I do have a concern about tire/rim damage. Any issues going to: 265/35/20 295/30/20 Anyone do this? Fitment issues? Rubbing? Trying to get a little more sidewall. The front to back ratio stays roughly the same and the speedo will only be a little off.
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01-10-2020, 06:02 PM | #2 | |
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01-11-2020, 08:04 AM | #4 |
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I'm now thinking that 245/40/20 and 265/35/20 may be the better option. Speedo will be off a little but the tire diameter ratio stays the closest this way. Will go with non-RFT.
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01-11-2020, 08:08 AM | #5 |
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Call Discount Tire and ask them. I went to 285 and 255 in 19” wheels and they told me they could absolutely confirm they would definitely fit with no issues, and I went to a 1/2 inch wider 7 series wheel. Obviously mine were different series, but the point is that they have a good data base of known fitments
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01-11-2020, 11:19 AM | #6 |
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Widest u can fit on 668 is 245 front, 275 rear. Tallest you can fit is 245/40/20 and 275/35/20.
If you want 265 and 295, you will need a 9" wide wheel in front and at least 10" wide wheel in rear. To prevent rubbing on 265/35/20, you need between 25-33(preferably 28-30)offset front. The rear has very much space to fit 295/30/20, any offset between 35-45 will be safe from rubbing even if lowered. |
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01-11-2020, 12:18 PM | #7 | |
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01-11-2020, 01:06 PM | #8 | ||
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01-11-2020, 02:22 PM | #9 |
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I have the 668Ms, 20 inch. I have had no problem since switching to Michelin PS3ZP runflats. Very smooth ride, much more grip, and have had no further sidewall damage (popped two of the Goodyear F1 Asymmetrics sidewalls which were OEM, without rim damage). Didn't change tire size, just bought better tires.
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01-11-2020, 03:42 PM | #10 | |
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So stock tire diameters are: 245/35/20 = 26.8 275/30/20 = 26.5 Ratio is 1 : 1.01132 With my proposed sizes, the tire diameters are: 245/40/20 = 27.7 265/35/20 = 27.3 Ratio is 1 : 1.01465 With 275/35/20 (diameter = 27.6), that ratio goes to 1 : 1.00362 So the ratio with 265/35/20 is closer to stock. Another way to look at it is that with stock tires, the fronts are .3 inches bigger in diameter. With 245/40/20 fronts and 265/35/20 rears, the fronts are .4 inches bigger in diameter but if I went with 275/35/20, the fronts would only be .1 inch bigger in diameter. Am I going about it incorrectly?
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01-11-2020, 04:07 PM | #11 | ||
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01-11-2020, 07:06 PM | #12 | |
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01-12-2020, 07:43 AM | #13 |
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You are of course correct. I feel 100% positive that BMW engineers are smart enough to figure that out
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01-12-2020, 12:33 PM | #14 | |
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Which is correct - maintain front/rear wheel diameter ratio or go for square all around like Superjackson says?
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01-12-2020, 03:04 PM | #15 |
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I upgraded sidewall when I got my car immediately to the sizes you are inquiring about. 245-40-20 F; 275-35-20 R with no issues. I went with Conti DWS06 NRFT. It's a very nice ride and I live in NYC area. Do it!
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01-12-2020, 07:03 PM | #16 | |
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But with today's complex ECUs, who knows.
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11-28-2022, 09:41 AM | #17 | |
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