??? Thank you in advance.

My tires feel sluggish at lower psi, but my concern is when I take a turn, exit ramp, switch lanes, or what ever type of turn with 35/33 psi my car is all over the road as if it were rocking like a boat. It feels much better with 39/37 psi, and I was just wondering if everyone else with this size tires on stock rims had the same problem. So do you?



[Modified by 01PYTypeR#1140, 5:46 PM 1/28/2002]

 

thats a very good question. Id like to know also...

 

what it says on the door frame +/- 1psi.

 

I usually run 37/F 35/R with my RE730's

 

34 all around on azenis

 

40 psi on Kumho Ectsa 712's

Tires feel sluggish at any lower psi.

 

35/33

Pressure is irrespective of volume (since it is a Force/Area metric).

 

My tires also feel sluggish at lower psi, but my concern is when I take a turn, exit ramp, switch lanes, or what ever type of turn with 35/33 psi my car is all over the road as if it were rocking like a boat. It feels much better with 39/37 psi, and I was just wondering if everyone else with this size tires on stock rims had the same problem. So do you?

 

All tires will differ as they all are made of different compounds, belt thicknesses and tread thicknesses. A lot depends on driver preference and driving style. Similarly, a lot will depend on the road surfaces you drive on and ambient temperatures.

You can determine optimal pressure in a number of ways. On the street - you never really heat up the tire (like you would at the track). At my track days a 20 psi change after a hard run is not uncommon. You can use shoe polish on the sidewall of the tire to determine the optimal pressure for your tires. It will show you how much of the tread is rolling over when you make hard turns. Adjust to higher pressures if you find you are scrubbing more onto the sidewall. Typically with stock spring rates and tires you will need higher pressure up front (i.e. understeering tendency due to nose heavy car).

Running higher pressures will make the sidewalls more firm and tend to improve turn-in and fuel economy, at the expense of steering effort (often too light), lowered traction (especially in the wet and off the line). You shouldn't run high pressures if you're doing long stints of highway driving in hot weather.

Running lower pressures will do the opposite - mushier turn in, lower fuel economy, better traction (up to a point). An underinflated tire is just as dangerous as an overinflated tire.

Find out for yourself. You will find you have a wide range of available pressures. I won't even delve into how pressures will affect setup for autocross as to not confuse you.

I often crank up the tire pressures when I get rent-a-cars. It's amazing how it will change the demeanor of a vehicle.

BUT DON'T USE AUTOCROSS PRESSURES!! - they are waaay too high.




[Modified by Big Phat R, 2:58 PM 1/28/2002]

 

37/35

Like mentioned, every tire is different so experiment.


[Modified by Cyberorth, 10:54 AM 1/30/2002]

 

36/34

Will

 

Yoko AVSi's 205/50 - so damn sluggish .... I hate them ..... I am forced to run 40-42 front and 38-40 rear. This fixes the floaty feel but very darty. Excessive wear in the middle of the tire (obviously) but I don't care ...... i wanna burn them.

You should expect a floaty feel when you go with 205/50's. The stock rim isn't the "perfect" width for those tires. (but are within the acceptable range)

Just try to find a tire with the stiffest sidewall as possible if you are going the 205 route. This will give you a better turn in with out that slight delay.
Its a trade off, larger contact patch but poo pooy initial turn in.

-nick

 

That is very true. The stock rims are a little too narrow for anything wider than the 010s.

 

Yes, I uderstand exactly what you are saying.

I went from the stock RE010's at stock pressure to the Michelin Pilot Alpin's in the 205/50/15's at stock pressures as well. Suffice to say the stock pressures although a good starting point to guage from, is WAY too soft for the Alpin's. It felt like I was driving on wet sponges. I have run a few Auto-X's and discovered that just a few Lb's of inflation or deflation makes a world of difference. After some time trying different pressures I discovered that a 40F/37R to be my favorite setting for daily driving.

Of course snow tires are supposed to be set when cold so the pressure changes by a few LB's when hot, max inflation being like 67 or 68 PSI for mine. I do however lower the PSI cold when expecting snow for more traction at lower speeds.

And: "BUT DON'T USE AUTOCROSS PRESSURES!! - they are waaay too high." Agreed! Especially if you haven't driven with higher pressures or at an Auto-X or track event. There are a host of reasons why not. One of the main one's being; the car tends to act totally differently and you may not be accustomed to it's response to your input.

All in all, different tires with different compounds and different construction act Well, DIFFERENTLY! And you have to drive each one to find the optimum settings to your liking.

Good luck,

A.

 

38/38 on RE730

 

35/38 on kumhos

 

After a little testing, I think I'm going to stick with 39F/37R thanks for all your post.