The "right" way to check tire pressure is to use a pyrometer and to
check the temperatures across the tire (three readings, inside, middle
outside). This, of course, is impractical unless you *want* to go
spend a couple hundred dollars on a pyrometer.
You don't mention which exact year and model car you have.
You also didn't mention spoke or steel wheels.
My BGT cornerweights out almost 50/50 with driver, so I run the same
pressure all around. At the moment, I'm running 35 PSI.
The front/rear skitteriness will be changed by the ratio of the
front/rear tire pressures. Judging by 70-series tires, R rated (not
SR, HR or VR) and the fact that you didn't mention brand and model,
I'd be willing to guess that your tires are not the grippiest tires on
the road. There is a good chance that no matter what you do to your
tire pressures, the car won't corner as well as one where someone
spent $5-600 on a set of tires.
On the street, the component that has the biggest effect on a car's
handling is the spacer that fits between the seat and the steering
wheel. I've seen students knock 20 seconds off their lap times in a
day of training. If you can't comfortably keep up with another
car/driver, don't try. Back off and get there safely. Back when I was
younger and stupider (New years eve of '85 as I recall) I spun and
rolled my Sprite trying to keep up with a Volvo station wagon on Hwy 9
( a windy road in the santa cruz mountains).
If you want to optimize your cars handling via tire pressure, the best
thing you can do, is to find a safe place to go out and
experiment. Are there any large empty parking lots near you? The
problem with roads is that if you make a mistake, there may be
something to hit right near the road.
Pump your tires up to "maximum" pressure all around. Take a notebook,
note your tire pressures, drive the car around, note the differences
in the notebook. Note the hot tire pressures, take a couple pounds out
of either the front or the rear. try it again, take a couple pounds
out of the other end. Lather, rinse repeat. Bring a tire pump or
portable compressor in case you over do it on letting air out. Don't
go much less than 30PSI if you'll be cornering hard, as rolling a tire
off the rim can lead to all sorts of unplannedfor excitement.
Larry
On Tue, Mar 04, 2003 at 08:44:18PM -0500, William Killeffer wrote:
> Hello,
> I've been thinking about tire pressure for some time, ever since a group
> of MG owners went on a spirited drive and I could barely keep up. Can't
> remember exactly what wasn't right, but I just couldn't make the turns
> as fast. The leader said to look into my tire pressure and recommended
> using the pressures on the glove box sticker (27 psi front, 32 rear, 155
> R14 radial tire).
> That doesn't seem right, as the car becomes twitchy at highway speeds,
> especially if a truck passes me. The handling didn't seem improved either.
> My tires are 185/70R14 because that's what came on it. The maximum
> pressure is 35 psi. They're about two years old but they probably don't
> have more than 7000 miles on them. My front suspension is almost all
> poly bushings with new Armstrong shocks. There is a sway bar up front.
> The back has new Armstrong shocks but no new bushings yet. The bushings
> that are there look reasonably intact. No rear swaybar. The wheels are
> rostyles.
> In order to get a more spirited and sure-footed ride, what tire pressure
> should I use? I ran a Google search and looked at Barney's page, but
> didn't find anything in black and white. I'm too brain dead right now to
> figure it out myself, but have a vacation day tomorrow to do some
> experimentation.
> Thank you,
> -Bill
>
--
I've found something worse than oldies station that play the music I used to
listen to. Oldies stations that play the "new" music I used to complain about.
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