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01-14-2024, 01:17 PM | #1 |
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Tyre size and pressure
Hi all
Looking for some advice on the sizes of my Tyres, I have 225/35/19 on the front and 225/30/19 on the rear. Is difference in profile usual? Also, what pressure should I be inflating to? Thanks for any advice in advance…. |
01-14-2024, 03:38 PM | #2 |
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Rear should be 255/30 19 not 225/30
225/35 19 and 255/30 19 are standard sizes on factory 19”rims 36/42 psi is the factory figures for oe runflats If you don’t have runflats different pressures apply
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Much modified 2011 Atacama Yellow 35is…previously a much modified 2012 Atacama Yellow 20i MSport
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01-14-2024, 10:28 PM | #3 |
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On Michelin website you can enter all your car details(mark model, engine, wheel and tire sizes) and it gives you recommended tire pressures.
for 19 inch stock tire sizes on a 35i it recommends 2.3 bar front and 2.8bar rear. The sticker in the drivers door jam/gap says 2.4 bar front and 2.9bar rear, thats the same as B21 said in psi.
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2009 35i DCT Havana brown with ivory white interior. Mods: Cobb stage 1+FMIC, Wagner EVO1 FMIC, BMS DCI, Forge DV-s, Masata Chargepipe, KW V3 suspension, M3 front control arms, Hardrace RTABS + balljoints, Michelin Pilot Sport 4S tires.
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Waftycrankers6.00 |
01-15-2024, 06:25 AM | #4 |
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Thanks for the replies this far. My error, the rears are 255/30/19 not 225.
Mine are not run flats. Unfortunately the sticker on the door jam is half torn. Not sure why. |
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01-15-2024, 07:12 AM | #5 |
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Yiu may find for non run flats that pressures in he range 32/34 through 36/38 are more beneficial..
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Much modified 2011 Atacama Yellow 35is…previously a much modified 2012 Atacama Yellow 20i MSport
Change history here… https://www.dropbox.com/s/8h1vabklgz...0List.pdf?dl=0 Build thread here… https://z4-forum.com/forum/viewtopic.php?t=131886 |
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01-15-2024, 03:21 PM | #7 |
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Hmm i wouldnt go too low from stock pressures at the rear... on 19 inch rims you can risk developing cracks on the inside edge of the wheel.
That edge is already lower than the outside edge because of negative camber. now if you lower tire pressure aka deflate tire you diminish the sidewall even more and risk banging that edge up. I remember years ago there were threads where people even suggested inflating rears past stock pressure to keep cracking from happening... 33 in the rear seems too low to me. My suggestion is to try it yourself... start with stock figures and slowly deviate from them and test. See what you prefer. For me i even notice from driving that tires are 0.2-0.3 bar low... Couple illustrations that were posted on this forum in 2010...
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2009 35i DCT Havana brown with ivory white interior. Mods: Cobb stage 1+FMIC, Wagner EVO1 FMIC, BMS DCI, Forge DV-s, Masata Chargepipe, KW V3 suspension, M3 front control arms, Hardrace RTABS + balljoints, Michelin Pilot Sport 4S tires.
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01-15-2024, 04:32 PM | #9 |
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For non run flats there’s no specific pressures…as discussed it’s best to experiment to see what works for you …personally I find 32/34 to 34/36 works for me..be that on 18” and 19”…
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Much modified 2011 Atacama Yellow 35is…previously a much modified 2012 Atacama Yellow 20i MSport
Change history here… https://www.dropbox.com/s/8h1vabklgz...0List.pdf?dl=0 Build thread here… https://z4-forum.com/forum/viewtopic.php?t=131886 |
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01-18-2024, 10:59 AM | #10 |
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I run 34psi all around, but B21's recommendation looks good to me. His lower front pressures helps negate some of the understeer. These cars need way more rear bar. I'm on H&R springs right now, but the balance is similar to stock.
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2017 BMW M4 Comp DCT blk/blk 2001 Porsche 911 Turbo 6sp blk/blk Last edited by Steve Jarvis; 01-22-2024 at 12:24 PM.. |
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01-18-2024, 06:30 PM | #11 |
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I'm on M4PS. 34 front, 38 rear. KWV3 and other suspension upgrades too. It's tits.
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