Tire pressure for 3.0Si coupe with non-run flats

baege · 03-09-2012, 01:41 PM

With the rise in temperatures, looking to ensure my tire pressure is in the correct range.

Did some searches and can't seem to find a definitive answer on what the tire pressure should be for a 3.0si coupe running the stock sizes 225/40 up front and 255/35 back with non-run flat tires (Pilot A/s +1 in my case)

Some say go stock 32-33 front, 37-38 rear

some say go 32-33 all around

I've been running 32-33 front 37-38 rear but I do find my ride a bit bumpy?

views?

v3.2mc · 03-09-2012, 02:50 PM

if your car is loaded with the optional sport package (zsp), then "bumpy" is what you'll be living with regardless of pressure. especially if you're on 18's or more.

i ran with 32 on all four corners with non-RFTs and 18's, but it was still pretty harsh. still... it was MUCH less harsh after ridding myself of the RFTs.

Shipkiller · 03-09-2012, 04:02 PM

What does the sticker say?

Hawkeye · 03-12-2012, 09:54 AM

There is a sticker in the drivers side door frame that should tell you. I believe it says low 30's.

Huz-Z · 03-12-2012, 10:54 AM

Quote:

Originally Posted by Hawkeye

There is a sticker in the drivers side door frame that should tell you. I believe it says low 30's.

Ditto!

baege · 03-12-2012, 12:01 PM

Quote:

Originally Posted by Huz-Z

Ditto!

The sticker is for the factory provided run flats
33 front 39 rear
There are opinions that those PSI values only pertain to run flats and so when you switch to non run flats the issue is open to debate

ruscoupe · 03-12-2012, 12:46 PM

The answer I've seen offered to the question most often, which I happen to agree with, is that there isn't a one size fits all answer. Too many variables, and they go beyond RFT vs non-RFT. One important consideration for example would be roads typically driven, particularly if the car is used as a daily driver.

Sure, there's a min/max recommended range for PSI, and that's usually what you're going to find on the door jamb unless you're running a completely different setup (in terms of size) than OEM, but other considerations vary depending on such things as tire brand, average ambient temperature (i.e., not the same for a car in Maine as it would be a car in Arizona), etc.

Rus

imz4n · 03-13-2012, 09:21 AM

I run Hankooks on my Si. For freeway driving 34 front and 40 rear. for tracking purposes I reverse that 40 front and 34 rear. I also had a alignment done and took out 1 deg of camber in the rear and added 2 deg of toe in in the front. This is from stock settings.

v3.2mc · 03-13-2012, 09:45 AM

Quote:

Originally Posted by imz4n

... added 2 deg of toe in in the front.

you did this on purpose?!

i've not heard of doing this before... what are the advantages?

imz4n · 03-13-2012, 10:16 AM

Quote:

Originally Posted by v3.2mc

you did this on purpose?!

i've not heard of doing this before... what are the advantages?

Seeing how I have less track time than normal driving.
The toe keeps the car from being twitchy ( wondering in the lanes going down the freeway ) not trambling issue. Side advantage it helps with turn in. Needless to say I do not have flat edges on the outside of the front tires. The front tires do not wear out on the outside edges. Not too much toe in to cause issues.

Shipkiller · 03-13-2012, 11:18 AM

TWO, TWO degrees of toe???? That will wear out a tire faster than anything else.

Plus, I cannot understand how that much toe would give you better turn-in. I have my toe set to zero, and that was a great improvement in turn-in feel.

Bob, are you pulling a fast one here??? I would not put it past you...

Hawkeye · 03-13-2012, 11:24 AM

Quote:

Originally Posted by baege

The sticker is for the factory provided run flats
33 front 39 rear
There are opinions that those PSI values only pertain to run flats and so when you switch to non run flats the issue is open to debate

You can debate all you want, but the sticker in the door is not just for runflats. It works perfectly fine with my non-rft, and if you had ever ran runflats you would not think your ride was bumpy in comparison.

You asked for an opinion and I gave you mine.

damikmak · 03-14-2012, 08:35 AM

Hawkeye has it right about the door sticker. 33 front and 39 rear. Works perfect on my 19 inch wheels with non runflats

sbtwister · 03-16-2012, 02:41 PM

I've got Michelin Pilot SuperSports, same size on 18" wheels, with M-Sport suspension. I asked the tire installer about proper pressure, they set it up as 36 psi - rear, 33 psi - front.
The rear does feel a little firm - but... it's a sports car.

XMetal · 03-17-2012, 10:59 AM

Wow...you guys are running on pretty high pressure for daily uses. My door jamb says 30F and 30R and I normally just run at 32F/R.

aerobod · 03-18-2012, 01:00 PM

I normally run 32F/30R for everyday use with summer or winter tyres. To get the right amount of sidewall flex with 245/40-18 front and 275/35-18 rear Dunlop Star Specs, I typically use 38F/34R for autocross and 36F/34R for trackdays.

santov · 03-18-2012, 09:45 PM

I think the door jamb sticker only applies to the OEM tires. I also don't think that +/- a few PSI is going to make a huge difference im ride.

Personally I ride at 75-80% max pressure printed on the side of the tire. I check constantly that the center of the tire isn't wearing more than the outter edges. I adjust the pressure accordingly. My hope is to get max MPG and max wear, both of which are supported by higher pressure, just so long as they wear evenly.

03-09-2012, 01:41 PM	#1
baege Lieutenant Colonel 1334 Rep 1,600 Posts Drives: 2022 Cayman GTS 4.0 6MT Join Date: Jun 2009 Location: Toronto, Canada iTrader: (0)	Tire pressure for 3.0Si coupe with non-run flats With the rise in temperatures, looking to ensure my tire pressure is in the correct range. Did some searches and can't seem to find a definitive answer on what the tire pressure should be for a 3.0si coupe running the stock sizes 225/40 up front and 255/35 back with non-run flat tires (Pilot A/s +1 in my case) Some say go stock 32-33 front, 37-38 rear some say go 32-33 all around I've been running 32-33 front 37-38 rear but I do find my ride a bit bumpy? views?
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03-09-2012, 02:50 PM	#2
v3.2mc Not a New Member 94 Rep 925 Posts Drives: with both hands and both feet Join Date: Mar 2012 Location: midwest iTrader: (4) Garage List 2007 ///M Coupé [10.00]	if your car is loaded with the optional sport package (zsp), then "bumpy" is what you'll be living with regardless of pressure. especially if you're on 18's or more. i ran with 32 on all four corners with non-RFTs and 18's, but it was still pretty harsh. still... it was MUCH less harsh after ridding myself of the RFTs.
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03-09-2012, 04:02 PM	#3
Shipkiller Colonel 187 Rep 2,138 Posts Drives: Me Join Date: Oct 2007 Location: Virginia Beach iTrader: (3) Garage List 2008 BMW Z4M Coupe [8.50] 2003 BMW Z4 Roadster [8.33]	What does the sticker say?
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03-12-2012, 09:54 AM	#4
Hawkeye Brigadier General 2070 Rep 4,365 Posts Drives: '07 Z4 Coupe, '21 X3, '16 GMC Join Date: Aug 2007 Location: Iowa iTrader: (0) Garage List 2016 GMC Sierra SLT [10.00] 2008 Yamaha R6 [9.00]	There is a sticker in the drivers side door frame that should tell you. I believe it says low 30's. __________________ 2007 Z4 3.0si Coupe • 6 MT • Black Saphire Metallic • PP • SP 2016 GMC Sierra SLT Z71 Premium Plus 4x4 2017 Harley StreetGlide • Denim Black • V&H Tune 2021 BMW x30i • Phytonic Blue Metallic • Fully loaded
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03-12-2012, 12:46 PM	#7
ruscoupe Private 4 Rep 99 Posts Drives: 2007 z4 3.0si Coupe Join Date: Oct 2011 Location: Texas iTrader: (1) Garage List 2007 Z4 3.0si Coupe [7.50]	The answer I've seen offered to the question most often, which I happen to agree with, is that there isn't a one size fits all answer. Too many variables, and they go beyond RFT vs non-RFT. One important consideration for example would be roads typically driven, particularly if the car is used as a daily driver. Sure, there's a min/max recommended range for PSI, and that's usually what you're going to find on the door jamb unless you're running a completely different setup (in terms of size) than OEM, but other considerations vary depending on such things as tire brand, average ambient temperature (i.e., not the same for a car in Maine as it would be a car in Arizona), etc. Rus __________________ Last edited by ruscoupe; 03-12-2012 at 02:40 PM..
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03-13-2012, 09:21 AM	#8
imz4n Captain 57 Rep 822 Posts Drives: 2006 3,0 si TITANIUM SIlVER Join Date: May 2007 Location: Orange County Ca. iTrader: (0)	I run Hankooks on my Si. For freeway driving 34 front and 40 rear. for tracking purposes I reverse that 40 front and 34 rear. I also had a alignment done and took out 1 deg of camber in the rear and added 2 deg of toe in in the front. This is from stock settings. __________________ SoCal Z Enthusiast contact me to get on the list. Events for like minded people and when you talk about your Z, we will know what you are saying. https://www.facebook.com/groups/ZSCCACalifornia/
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03-13-2012, 11:18 AM	#11
Shipkiller Colonel 187 Rep 2,138 Posts Drives: Me Join Date: Oct 2007 Location: Virginia Beach iTrader: (3) Garage List 2008 BMW Z4M Coupe [8.50] 2003 BMW Z4 Roadster [8.33]	TWO, TWO degrees of toe???? That will wear out a tire faster than anything else. Plus, I cannot understand how that much toe would give you better turn-in. I have my toe set to zero, and that was a great improvement in turn-in feel. Bob, are you pulling a fast one here??? I would not put it past you...
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03-14-2012, 08:35 AM	#13
damikmak Enlisted Member 2 Rep 45 Posts Drives: 2007 Z4 3.0si Coupe Join Date: Oct 2010 Location: SoCal iTrader: (0)	Hawkeye has it right about the door sticker. 33 front and 39 rear. Works perfect on my 19 inch wheels with non runflats Last edited by damikmak; 03-16-2012 at 11:00 PM..
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03-16-2012, 02:41 PM	#14
sbtwister Private 0 Rep 52 Posts Drives: 2005 3.0i Z4 Roadster Join Date: Jun 2010 Location: Santa Barbara, CA iTrader: (0)	I've got Michelin Pilot SuperSports, same size on 18" wheels, with M-Sport suspension. I asked the tire installer about proper pressure, they set it up as 36 psi - rear, 33 psi - front. The rear does feel a little firm - but... it's a sports car. __________________ Alpine white Z4 3.0i, Dream red leather, M-sport seats, Sport package, Xenons, Heated seats, Premium sound, XM Radio, Aux in, Strut brace, Black grill, CF Roundels, Stubby, Half foam.
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03-17-2012, 10:59 AM	#15
XMetal Colonel 1135 Rep 2,866 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	Wow...you guys are running on pretty high pressure for daily uses. My door jamb says 30F and 30R and I normally just run at 32F/R.
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03-18-2012, 01:00 PM	#16
aerobod Car Geek 3626 Rep 3,594 Posts Drives: Caterham R500, M2-G87, Macan S Join Date: Mar 2008 Location: Calgary iTrader: (0)	I normally run 32F/30R for everyday use with summer or winter tyres. To get the right amount of sidewall flex with 245/40-18 front and 275/35-18 rear Dunlop Star Specs, I typically use 38F/34R for autocross and 36F/34R for trackdays.
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03-18-2012, 09:45 PM	#17
santov Lieutenant 64 Rep 483 Posts Drives: 2007 Z4 3.0si White over Beige Join Date: Dec 2010 Location: Bay Area, Calif iTrader: (8)	I think the door jamb sticker only applies to the OEM tires. I also don't think that +/- a few PSI is going to make a huge difference im ride. Personally I ride at 75-80% max pressure printed on the side of the tire. I check constantly that the center of the tire isn't wearing more than the outter edges. I adjust the pressure accordingly. My hope is to get max MPG and max wear, both of which are supported by higher pressure, just so long as they wear evenly.
	Appreciate 0 Quote