znod

thanks for your reply.
yes the car is now at 34F:36R and it feels a bit sluggish off the line, done nore grip instantly and the front feels a bit floaty over the road. what do u run the pressures at?

Andrew
[/quote]
I see. I thought you were worried about wheel spin. I go with about 34 R and 32 F. I would imagine your inflation would create a sluggish feeling unless way low, say, somewhere below 30 psi.
[/quote]

not sure waht u mean? you would "not imagine"?
also, its most noticeable ont he highway, does that mean i need more PSI or Less?
[/quote] I mean I don't think your inflation should create a sluggish feeling, off the line, unless way low, say, somewhere below 30 psi.


I am going the right direction since I am emphasizing straight lines not curved lines.

smcd

I am going the right direction since I am emphasizing straight lines not curved lines.
[/quote]Please explain what you mean by "right direction" - what is better about your pressure settings for straight lines?

- Sean

znod

Please explain what you mean by "right direction" - what is better about your pressure settings for straight lines?

- Sean
[/quote]Tell me what you mean by "wrong direction" first. ~{;^)

smcd

Please explain what you mean by "right direction" - what is better about your pressure settings for straight lines?

- Sean
[/quote]Tell me what you mean by "wrong direction" first. ~{;^)
[/quote]By wrong direction, I mean that your rear tire pressure is higher than your front. This doesn't help with acceleration or handling. It just makes the car understeer more which is "safer".

znod

Please explain what you mean by "right direction" - what is better about your pressure settings for straight lines?

- Sean
[/quote]Tell me what you mean by "wrong direction" first. ~{;^)
[/quote]By wrong direction, I mean that your rear tire pressure is higher than your front. This doesn't help with acceleration or handling. It just makes the car understeer more which is "safer".
[/quote]
By "right direction," I indicated that I was emphasizing straight lines. Thus, more in the rear is acceptable if you don't have a traction problem and things are feeling sluggish as he mentioned. My thought was that, all things considered, he would end up less happy with more in the front. Also, he was looking for an overall optimal solution--where no solution dominates all others from an overall perspective. However, for me the best overall solution for the street is more in the rear since I drive mostly in straight lines and don't have a traction problem. I'll bet he drives most in straight lines too and only occassionally drives curves fast, but, of course, I could be wrong on this supposition. Anyway, a more-in-the-rear solution may be best for him. And, admittedly, I ignored the idea that he did not care about ride. For ride, I prefer more in the rear. BMW recommends more in the rear and high inflations--probably mainly for safety and ride concerns.

smcd

andrewnicholas is clearly looking for a performance/handling solution (re-read the title & content of his post!). I don't think that your recommendations are helpful in this regard although you are clearly happy with the settings yourself.

My recommendation for performance + cornering is lower rear and higher front. You might even consider trying it yourself for a while to see the difference. More in the rear will NOT help with sluggishness & will add understeer that you need to fight with in the corner. Higher front lower rear is faster off the line AND corners better. I think I'm done repeating myself now.

andrewnicholas

andrewnicholas is clearly looking for a performance/handling solution (re-read the title & content of his post!). I don't think that your recommendations are helpful in this regard although you are clearly happy with the settings yourself.

My recommendation for performance + cornering is lower rear and higher front. You might even consider trying it yourself for a while to see the difference. More in the rear will NOT help with sluggishness & will add understeer that you need to fight with in the corner. Higher front lower rear is faster off the line AND corners better. I think I'm done repeating myself now.
[/quote]
hey,
thanks for all the input, but just wondering do you have a 2006 530i w/sport?
just ask cuz as far as i know, and my experience, trying to put more in front than in the back expecially a dramatic difference makes the steering feel light and bumpy at speed and whne u accelertate, it feels liek the front just slides forwards instead of gripping and creating and opposing force for the rear to push against.

znod

andrewnicholas is clearly looking for a performance/handling solution (re-read the title & content of his post!). I don't think that your recommendations are helpful in this regard although you are clearly happy with the settings yourself.

Gee, maybe I answered the wrong question. ~{;^) I guess the topic-starter will need to decide for himself what he likes best. Note that he said the following in his first post.

"So as u can imagine, i am a bit confused and annoyed,. I mean, there must be one set of tire pressures to maximize both straight line performance and cornering grip ....

So far, 34F:36R feels the best, but still not great...my last bmw a 2003 330i, you could feel the communication between the front and the rear, the reacted at the same time, hoever, with this car and the ttire presssures givien to me, i cannot say the same."

So, "clearly" he is interested in both types of performance. Maybe, he'll try your suggestion and like it better.

My recommendation for performance + cornering is lower rear and higher front. You might even consider trying it yourself for a while to see the difference. More in the rear will NOT help with sluggishness (I only suggested that adding air might negate sluggishness if his rears were quite low--see earlier post) & will add understeer that you need to fight with in the corner. Higher front lower rear is faster off the line AND corners better. I think I'm done repeating myself now.

Yep, quite a lot. ~{;^) As indicated, I was talking straight lines and street driving. You are talking about taking frequent curved lines at speed. Let's just let him decide at this point. Why do you presume that I have never driven a car with lower rear and higher front?
[/quote]

smcd

I am NOT just talking about curves. READ MY POSTS. And as I said, straight line acceleration is BETTER with higher front and lower rear.

I made that assumption as what you were saying appeared incorrect to me.

znod

I do not own a 530i sport. The physics are the same for all rear wheel drive (RWD) cars of which I have owned several including my 1995 M3 race car.

I'm not sure what you mean by the steering being lighter - it's certainly sharper - i.e. it turns more quickly & easily. It may be bumpier as the tire is less soft causing the overall suspension package (i.e. including tire) to stiffen.

The goal of the front wheels in a RWD car is to turn the car when cornering and do as little as possible when accelerating other than keep the car going straight. The higher tire pressure in the front causes less rolling resistance which will result in better acceleration. This is true for bicycles, motorbikes, cars & trucks. It's just physics at work.


I am NOT just talking about curves. READ MY POSTS. And as I said, straight line acceleration is BETTER with higher front and lower rear.

I made that assumption as what you were saying appeared incorrect to me.
[/quote]
PLease don't shout at me. Doing so is very impolite. You need to read my posts and replies more carefully. You are struggling against a strawman.

I do agree that you also are talking about straight-lines at least some of the time (note that I said "you are talking about taking frequent curved lines at speed"--which does not contradict the idea that you also are interested in straight lines--as acknowledged in my earlier posts), but given my explicit or implicit assumptions, my straight-line solution is better all around IMO. It's fine with me if you like yours better than mine. As said above, let's let him choose at this point. Maybe he will let us know what he likes best.