12-18-2020, 11:39 PM | #1 |
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tire size
In the M850i the 20" p zero are stock tires.
245/35R20 and 275/30R20. I know people put 21" and lowering springs, so I'm guessing stock - you can probably gain an fraction sidewalls? Does anyone know if 245/40-20 and 275/35-20 will run without problems? |
12-19-2020, 12:52 AM | #2 |
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As far as the variance goes (40 vs 35 on FRONT and 35 vs. 30 on REAR), below are the results.
FRONT Will fill out the wheelwell by extra 12 mm. Acceptable for most cars Negative scrub radius (about -4 mm). Almost no difference. Please be aware that calculated value is approximate. When speedometer reads 60 km/h actual speed will be 62.2 km/h REAR Will fill out the wheelwell by extra 14 mm. Make sure that you have enough room under the fender. If not, consider lower profiles or smaller rims Negative scrub radius (about -5 mm). Scrub radius will be changed by -5 mm, this may affect the car's handling. Please check manufacturer recommendations. Please be aware that calculated value is approximate. When speedometer reads 60 km/h actual speed will be 62.5 km/h I usually turn to this site it's very precise and you get the decisive values and parameters in regard to variance between stock and the desired setup: https://www.wheel-size.com/calc/ Also consider there will be added weight as well. Technically you can drive it and should not have any issues as scrub radious is minimum and many cars (setup) come with a slight negative scrub radius already. Though, I'd ask a professional tire/car shop just to be 100% on the safe side before installing. |
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Slack Beries41.00 bloozemanAZ4275.50 |
12-19-2020, 09:28 AM | #3 | |
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FBMWWINS604.50 bloozemanAZ4275.50 |
09-11-2021, 07:26 AM | #4 |
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Did you try this setup?
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09-11-2021, 12:43 PM | #5 |
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BeamerandBimmer117.50 bloozemanAZ4275.50 |
09-11-2021, 02:56 PM | #6 |
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This is a genuine question, apologies if I seem dumb, what's the benefit of running oversized tyres? Have the wrong speedo reading would drive me OCD crackers but I obviously don't get the whole picture.
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09-11-2021, 07:06 PM | #7 |
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Looks. It looks like you put lowering springs or bigger wheels on it. Gives the appearance of a full wheel well. 21" vs 20" tires.
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09-12-2021, 02:48 PM | #8 |
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09-13-2021, 10:30 AM | #10 |
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Don't worry, it's wrong anyway. I think there's something like a 5% tolerance. You could also tell iDrive you have a bigger wheel to try to offset the bigger tire, but I believe you're getting some free miles on the odometer if you don't as well.
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Resjudicata1604.00 bloozemanAZ4275.50 |
11-16-2021, 12:09 AM | #11 |
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Debating going 21" or 20" with bigger tires. I know you decided to go with the bigger tire option, any pics?
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11-16-2021, 05:00 PM | #12 |
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Also, if you live in a pothole town, the larger sidewall protects the rim a bit more from damage.
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11-17-2021, 01:48 AM | #13 |
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11-17-2021, 08:36 AM | #14 |
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I feel like if I squint really hard when I hit a big pothole, it prevents the tire/wheel from getting damaged 😅
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11-17-2021, 08:49 AM | #15 |
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Way better to lift your feet off the pedals and floor and pinch real tight.
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01-21-2023, 09:02 AM | #17 |
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I still have stock 20” wheels, but replaced the stock run flat summers with Continental ExtremeContact DWS06+ with 40 front/35 rear sidewalls. Looks a lot better, rides better and is much quieter. No decrease in handling. Had the setup for 10 days.
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01-22-2023, 03:11 PM | #18 |
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Better shot I did today. After her first foam bath and wax.
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01-22-2023, 03:25 PM | #19 |
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Excellent and as previously stated my next go to when the new set of P Zeros run their course. Always ran Continentals on my prior sport sedans with all the grip needed for every day plus spirited driving. Plus throw in the extra tread life and a total win-win.
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01-22-2023, 03:30 PM | #20 |
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Hit one yesterday in an unknown areas of town which was more of a crack in the street vs a pothole so didn't see it until too late. Friend in the car with me got an ear full of WTF and a couple of further rants. He has no clue what a pothole can do on 20" rims with little rubber between them and the road.
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01-22-2023, 03:33 PM | #21 |
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Which brings up a point from older threads in which oversized tires caused issues with X drive and the dealers not wanting to cover the drive train issues due to that. Is this setup of sizing immune to that?
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01-22-2023, 04:06 PM | #22 |
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Did you bend a rim? The upsize in tire has been no issue from my dealership (bmw of Manhattan) they did it for me and suggested it.
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snowbimmer5269.00 Accentu8705.00 |
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