04-09-2017, 01:04 PM | #23 | |
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What OEM tire pressure is recommended in your door panel? |
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04-26-2017, 10:34 PM | #24 |
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I have the distinct impression most who install 437m on F3x vehicles and F3x specs are going to be buying new tires pretty fast.
Now the question will be....will more admit it. |
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05-27-2017, 07:32 PM | #25 | |
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The pressure is another thing. Going too low, esp on 20", compromises the car's performance. The best numbers I had were 4.3 to 4.4 s 0-60s. Fiddle with the pressure and the number go up. In my case, 20" were brutal in Canada, where road issues- just once or twice a year- meant one bent wheel and vibrations. Alignment is a must. After going to Ray's top grade wheels, 235/40 -19 AND 275/35-19, WIDER, saved 26 lbs vs 405M and 43 lbs vs 361M, handling, everything is improved dramatically. So to improve handling, the true solution is -1.3deg, close to recommended PSI (or below for non RFT's), and suspension tuneup e.g. Dinan. |
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06-01-2017, 05:27 AM | #26 | |
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Rear is where it gets interesting. Non M cars have understeer built in. xDrives are also heavier in the front, by a bit. Consequently, even though the calculator would reveal ridiculously low numbers for the rear (using the formula, my 275 Michelin should be 28 PSI), in reality it has to be stiffer than the front to compensate for the understeer. In the 20" format, they added 6 PSI. On a Michelin, I would start with 4. So if you have 34 front, rear should be no more than 37-38. If lowering front to 33, rear 36-37. However, I tried 32 front, and it was SOOO MUSHY. Finally, if 37 is too high for the rear, you get what a lot of people ended up having, 34-35 all around. As if not enough, the suspension also plays a role. More body roll in non-M cars means that the lower pressure equals, as I had, outer wear on my rears. Had to decrease camber, and keep the pressure a bit higher, and it resolved it, but took me 2 Pirelli sets. SO what works for a lighter M does not work for a non M. And if you add max load, with people- an unusual way of driving an M, then PSI is most likely higher in the book. In addition, M's are meant to be tracked, and many do track them. Pressure goes up a lot, so that M could be skirting 36 front 40 rear, even if starting at 32. So if driven in normal conditions, spirited, am not sure I would use 32. Last edited by Musashi; 06-01-2017 at 05:38 AM.. |
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