Tire pressures for aggressive high hp street / autocross

335boston · 10-17-2023, 12:37 AM

Hey guys ,

I’ve been trying to find an answer to this question and there’s just so many differnt answers that I’m now super confused . I have a single turbo n54 and bought a set of Federal 595 rs-pro tires (200 tread ware) and am trying to figure out ideal pressure for them. I’m running 235/40/18 front 265/35/18 rears. I’ve tried 36psi cold all around and 38 psi front 40psi rear (both cold) . Don’t really like the feel of either , is there a set up anyone likes on the street for most grip and handling ? I also hit high speeds as wellz Would love to reduce understeer if possible , thanks in advance!

335i54n · 10-19-2023, 06:07 PM

its all subjective but usually goes hand in hand with camber setting imo. i am all about even tire wear for my driving and let handling fall where it may. with -1 camber front and rear i run f-46, r-32-36psi. front need a lot of psi to prevent tire roll over otherwise add more camber and less psi, the better/grip rear tire need less but e90 rear dynamic camber is not good so can eat the inside if too low.

335boston · 10-19-2023, 10:11 PM

Quote:

Originally Posted by 335i54n

its all subjective but usually goes hand in hand with camber setting imo. i am all about even tire wear for my driving and let handling fall where it may. with -1 camber front and rear i run f-46, r-32-36psi. front need a lot of psi to prevent tire roll over otherwise add more camber and less psi, the better/grip rear tire need less but e90 rear dynamic camber is not good so can eat the inside if too low.

Hey man! I’ve got maybe -1.8 up front whatever is sort of max for pins pulled and m3 front arms. I’m sorta fine with extra ware if it’s to help aid in performance / handling . It’s not a daily just my weekend fun car.

Mrmigs2011 · 10-20-2023, 12:16 AM

I usually run 32 all around on fast road so that when I lock heat in the pressure drags itself up to the 36 psi range (not to mention the front stoppers generate hell of a load of heat)

However recently trialing 36 psi all around as fronts looked like they were rolling a bit and the car does seem a bit more sure footed with the stiffer side wall.

Only difference with mine is I'm square at 255/35/18. Might be worth starting from scratch to find your optimals, maybe even chalking. For normal road I think 36f 33r may be best place for daily (best contact patch anyway).

Running m3 arms and pins removed with -2 on the rear also camber wise.

I will say 32 is very comfortable and compliant over bumps where as 36 is more surefooted albeit more skittish per say but love the additional response!

335i54n · 10-20-2023, 10:16 AM

225/235 is just not enough front tire when you push it, 255/35 up front or even 245/40 makes a huge difference along with a front swaybar. with what you got try 40/32

335boston · 10-23-2023, 01:30 AM

Hey guys thanks for the reply’s !

What do you guys think of 35 front 32/33 rear? I’m only a little worried about psi under high speeds , I know the bmw booklet says something about needing minimum psi for higher speeds above 100mph

Might also look at increasing from size I have a 9 base rim on it so I have room but worried about rubbing . Also when I bought the wheels apex told me that I had to use the 235 with the 265 for something about optimal balance . Can you do a 245 with 265 out back? I think 265 is max on the e92 non m

Really looking for the most sporty set up , as it’s not a daily and just sorta taking it out to have fun with.

10-17-2023, 12:37 AM	#1
335boston Lieutenant 55 Rep 521 Posts Drives: 2008 335i coupe Join Date: Jul 2018 Location: Boston iTrader: (0) Garage List 2008 335i [0.00]	Tire pressures for aggressive high hp street / autocross Hey guys , I’ve been trying to find an answer to this question and there’s just so many differnt answers that I’m now super confused . I have a single turbo n54 and bought a set of Federal 595 rs-pro tires (200 tread ware) and am trying to figure out ideal pressure for them. I’m running 235/40/18 front 265/35/18 rears. I’ve tried 36psi cold all around and 38 psi front 40psi rear (both cold) . Don’t really like the feel of either , is there a set up anyone likes on the street for most grip and handling ? I also hit high speeds as wellz Would love to reduce understeer if possible , thanks in advance!
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10-19-2023, 06:07 PM	#2
335i54n Lieutenant 295 Rep 525 Posts Drives: e90 335i, e39 m5 Join Date: Nov 2020 Location: socal iTrader: (0)	its all subjective but usually goes hand in hand with camber setting imo. i am all about even tire wear for my driving and let handling fall where it may. with -1 camber front and rear i run f-46, r-32-36psi. front need a lot of psi to prevent tire roll over otherwise add more camber and less psi, the better/grip rear tire need less but e90 rear dynamic camber is not good so can eat the inside if too low.
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10-20-2023, 12:16 AM	#4
Mrmigs2011 Private 26 Rep 66 Posts Drives: 2006 E92 335i Join Date: Aug 2023 Location: Barton Upon Humber iTrader: (0)	I usually run 32 all around on fast road so that when I lock heat in the pressure drags itself up to the 36 psi range (not to mention the front stoppers generate hell of a load of heat) However recently trialing 36 psi all around as fronts looked like they were rolling a bit and the car does seem a bit more sure footed with the stiffer side wall. Only difference with mine is I'm square at 255/35/18. Might be worth starting from scratch to find your optimals, maybe even chalking. For normal road I think 36f 33r may be best place for daily (best contact patch anyway). Running m3 arms and pins removed with -2 on the rear also camber wise. I will say 32 is very comfortable and compliant over bumps where as 36 is more surefooted albeit more skittish per say but love the additional response!
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10-20-2023, 10:16 AM	#5
335i54n Lieutenant 295 Rep 525 Posts Drives: e90 335i, e39 m5 Join Date: Nov 2020 Location: socal iTrader: (0)	225/235 is just not enough front tire when you push it, 255/35 up front or even 245/40 makes a huge difference along with a front swaybar. with what you got try 40/32
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10-23-2023, 01:30 AM	#6
335boston Lieutenant 55 Rep 521 Posts Drives: 2008 335i coupe Join Date: Jul 2018 Location: Boston iTrader: (0) Garage List 2008 335i [0.00]	Hey guys thanks for the reply’s ! What do you guys think of 35 front 32/33 rear? I’m only a little worried about psi under high speeds , I know the bmw booklet says something about needing minimum psi for higher speeds above 100mph Might also look at increasing from size I have a 9 base rim on it so I have room but worried about rubbing . Also when I bought the wheels apex told me that I had to use the 235 with the 265 for something about optimal balance . Can you do a 245 with 265 out back? I think 265 is max on the e92 non m Really looking for the most sporty set up , as it’s not a daily and just sorta taking it out to have fun with.
	Appreciate 0 Quote