10-09-2023, 10:44 AM | #23 | |
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Street tyres such as the MPS4S will often give optimum grip at hot pressures in the low to mid 40s on a car the weight of the G87 at tyre temperature of 60C or so. A more track orientated tyre such as the AR-1 will need to be at 80C with more of a pressure rise. With AR-1s on my Caterham (which weighs 620kg with me in it), on the track I tried cold pressures all the way from 14PSI to 24PSI (18PSI optimum for the road) and 21PSI cold pressure gave the best grip and most even tyre wear at the optimum 28PSI hot pressure. |
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10-09-2023, 10:49 AM | #24 | |
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10-09-2023, 11:42 AM | #25 | |
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The one item I find confusing (or even lacking clarification) is the refer to the "M Package" which I assume is just the higher top end mph (limiter removed/adjusted). If so, as most driving would not be at that speed, would one really want to adjust for that figure? |
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10-09-2023, 12:29 PM | #26 | |
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10-09-2023, 03:45 PM | #27 | |
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The placard in the M2 is the least informative of all BMWs, it just says “read the manual, or 32”. Other BMWs had the tire pressures on the placard too. Aerobod posted the image of the manual for reference on page 1, if not handy. |
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10-10-2023, 09:22 AM | #29 |
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mine fluctuates in the cold/heat from 36-40 all 4. car feels great. have the PZeros which I wasn't thrilled about, but it poured all weekend and the car handled it perfectly. Not sure if this helps lol.
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10-11-2023, 07:54 AM | #30 | |
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The M Package tires have the highest cold pressure setting for both up to 100mph and over 100mph. |
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10-16-2023, 03:03 PM | #31 |
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Interesting discussion. I don’t have the drivers pack and have standard Michelin tires, here is what my car is saying. It has been in the garage two weeks while traveling. Not sure how it determines it needs 33.1 psi.
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10-17-2023, 09:21 AM | #32 |
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Yeah that's mine too, recommends 33.1 normally however I just checked it and now it recommends 33.9, but the weather is starting to get colder.
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10-17-2023, 02:16 PM | #33 | |
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I was seeing a recommended pressure when iDrive was set to “auto” tire type. But now that I have selected “summer” the app no longer shows a recommended pressure. |
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01-07-2024, 05:02 PM | #35 |
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I wonder the same. Mine says 33.9 front, 33.1 rear. I wonder what’s going on.
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01-07-2024, 09:55 PM | #37 |
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01-07-2024, 09:59 PM | #38 | |
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Tires are always at different temperatures, I see what you see all the time. What you can do to validate the pressures and system is wait until the tires cool down and go back in the car, turn it on so it reports the new values, and then look in the app later. Then it should read the same value all around. |
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01-08-2024, 06:26 AM | #39 | |
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01-11-2024, 09:06 AM | #41 |
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In Arizona yesterday it was 28° when I left for hiking at 7AM- tire pressures were 30psi. Later in the day, as temperature rose, tire pressure increased to 32psi. My rule of thumb for all our cars is to set pressure at the average, most likely, normal, seasonal outside temperature or something like that. Pressure will vary, period.
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01-12-2024, 08:50 AM | #42 | |
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The tire inflation pressure specifications in the tire inflation pressure table only relate to cold tires or tires at the same temperature as the ambient temperature. Only check the tire inflation pressure levels when the tires are cold, i.e.: ▷ A distance traveled of max. 1.25 miles/2 km has not been exceeded. ▷ If the vehicle has not moved again for at least two hours after a trip. You should set the tire pressures for the coldest ambient temperature. At 28F and 30psi the tires were under inflated. |
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01-12-2024, 10:26 AM | #43 | |
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Rule of thumb it is. |
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01-12-2024, 10:36 AM | #44 |
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Not only is 40/45 too high, it is also super-understeery setup. With more weight up front, you want square pressure or slightly higher front pressure to compensate for more weight and to get better turn-in response.
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