Maybe I can help, but the questioner's definition of "better" would make it easier for us to help.
If you increase the pressure of the rear tires, it will induce over-steer (more tendency, not spin-out over-steer)in relation to how much pressure you are increasing. If you increase the pressure of the front tires, it will induce under-steer. Over-steer will make the car feel like it turns in quicker, under-steer the reverse.
More pressure harsher ride, less pressure softer ride.
More pressure better gas mileage, less pressure worse gas mileage.
If your racing, first chalk the tire from inner sidewall to outer sidewall right over the face of the tread. Do a lap and you will see how much you are/are not running up onto the sidewall. If you are running up on the sidewalls, add air pressure. If not enough subtract air pressure.
The air pressure affects the aspect ratio of the contact area of the tire, which affects lateral handling and straight line braking. More pressure (within reason) elongates the contact area to more of an oval with the longer parts front-to-rear, better for braking. Less pressure makes the contact patch more circular thus making it wider than the previous oval contact patch example and will enhance lateral turns.
If this does not answer your question, then I would recommend my fellow members previous answer of following the door jamb sticker.

 

Well, as I stated, on the BMW I currently own, the door jamb, the manual, the dealer, and tire manufacturer (Michelin) do not provide the same information. Amazing. By clearly being too illiterate to comprehend my post, you've proven both my point and yours at the same time. I do agree with you, however, that your intelligence might best be represented by a dram, which is approximately 1/8 of an ounce. Not much in my book, but if you choose to self-identify as such, that's certainly your right.

 

Thanks Pennetta for your detailed explanation. This is what this forum is all about, the people who has more knowledge contributing. Don't we all who drive cars knows that the basic recommended information is posted by the door for the past 30 years. Each person has their own preference and just by sharing thoughts, that we gather this information and at the end of the day each to make their own judgement whats best for their own cars and driving pleasure/needs. Thanks CWS530 for your thoughts too.

 

Testy aren't we?

 

Yes. I regret saying that. Not cool.

 

Since you have different wheels/tires on your car now, I'd start with 32lbs and go up/down in 2lb increments until you find what's best for you. I've always ran mine in the 30 - 32 lbs range - with the exception of the BMW which is the 1st car I've owned that has different pressure requirements between the front and rear tires. I'd be cautious using the max air pressure on the sidewalls as I've seen pretty high max amonuts on various tires (up to 44 - 50lbs) and that would be way too much air (IMO). Another thought, is with the lower sidewall tires, I don't imagine you want to be running on the low pressure side....short enough sidewalls as it is....too low and I'd think you might be in danger of pinching the sidewall over potholes, etc.

 

Slightly off topic here: My wife's Cayenne calls for 39psi front/49 psi rear. I did a double-take because I couldn't believe how high Porsche was recommending. Granted the Cayenne's pretty heavy but still, 49psi? Anyways I took them down to 35/39 and it rides much better now.

 

I run 34 all round.

It's almost 50-50 weight balanced and there is no reason to have a higher pressure for rear tires unless you have rear passengers frequently. Higher rear pressure could cause understeer too.

 

35 all 4 tires

 

Not surprising. The pressures listed in the manual for the 19" tires on my 550 are 35 Front/39 Rear under 100mph, and 38 Front/45 Rear over 100mph.

I don't know what size you 19s are, but mine are 245/35 front 275/30 rear.