01-14-2023, 03:33 PM | #89 |
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01-14-2023, 03:53 PM | #90 | |
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How is your new speed compared to Waze? |
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01-14-2023, 04:13 PM | #91 | |
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After all, the GPS speed isn't as accurate due to elevation and numerical errors. I use https://tiresize.com/comparison/ to calc the differences. Factory front 21": 275/40R21 New front 21": 275/45R21, sidewall +14%, circumference +3.4% Factory rear 21": 315/35R21 New rear 21" 315/40R21, sidewall +16.3%, circumference +4% I inflated all new tires according to the factory psi (despite the size difference). Theoretically, the travel distance is 103.4% of the odometer distance. The new tires have softer sidewalls, though. |
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01-15-2023, 11:15 AM | #92 | |
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My other BMWs have inaccurate speedometers, are RWD, so tire size often times is not as relevant. In the X5, I found the speedometer to be pretty accurate so I wanted to know what differences these bigger tires had not he speedometer. |
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01-16-2023, 03:28 AM | #93 | |
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I was talking to a colleague who wrote an algorithm that uses ground stations to improve the accuracy of some special GPS receivers. In short, GPS positioning accuracy is about 3 meters. The instant speed of the receiver is calculated from positions. If driving on a flat road, instant GPS speed readings can be off by about 20% at worst. Signal reflections and interference can make matters worse. But if you're driving on an open field, like a runway at a constant speed, he says the readings are within 2-3%. Under normal driving conditions, he said he wouldn't trust the GPU's instant speed readings. |
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02-15-2023, 11:53 AM | #94 |
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How are all these tires size so far? Are these the MICHELIN PILOT SPORT 4 SUV?
More pic at normal height? Thanks I want to get rid off my Pzero RF and go 45/40 on the MICHELIN PILOT SPORT 4 SUV.
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02-17-2023, 06:27 AM | #95 | |
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Tires have been great no complaints work as they should.. these are the Michelin primacy your a/s |
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06-17-2023, 11:27 AM | #96 |
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I would like to go this route, but do not have air suspension. Any issue there? Do I still have the option to update the sizes in the computer to the 275/45 and 315/40?
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06-17-2023, 11:31 AM | #97 |
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Also noticing that these Michelins are not XL rated. Any concerns there?
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06-17-2023, 11:39 AM | #98 |
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06-18-2023, 05:11 PM | #99 | |
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06-18-2023, 06:44 PM | #100 |
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06-20-2023, 05:35 AM | #102 |
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I’m also interested in making the switch to taller 21” tires. Waiting to hear long term reviews.
I have a 24 X6 40i with ID8. There’s a setting for automatic detection of tires, I wonder whether it can pick up non standard tires and compensate the spedo accordingly. |
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06-28-2023, 07:37 PM | #110 |
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