Corolla FWD Tire Pressures

Rod wrote:[color=blue]
> Since the front wheel drive Corollas (I have a 2005) have the reverse
> situation, would it make sense to reduce the rear tire pressures a few
> psi less than the front, especially if the car is normally used with
> just the driver? I'd also be interested in your thoughts on handling
> effects if this were done.[/color]

Use the car manufacturer's recommendations for tire pressure.

"Travis Jordan" <no.one@no.net> wrote in message
news:6H1Ud.3182677$B07.503662@news.easynews.com...[color=blue]
> Rod wrote:[color=green]
>> Since the front wheel drive Corollas (I have a 2005) have the reverse
>> situation, would it make sense to reduce the rear tire pressures a few
>> psi less than the front, especially if the car is normally used with
>> just the driver? I'd also be interested in your thoughts on handling
>> effects if this were done.[/color]
>[/color]

The effect of dropping the rear pressure relative to the front is to promote
under-steer. This is a characteristic you car already has to excess.

Richard.

would it make sense to reduce the rear tire pressures a few
psi less than the front, especially if the car is normally used with
just the driver? *I'd also be interested in your thoughts on handling
effects if this were done.
------------
Would make more sense to increase the front by a few pounds.
My guess is that in the interest of safety, Toyota calls for all four
tires to use the same air pressure.
With the extra weight in the front, those tires are loaded more heavily
for the weight they're carrying than the rear.
In my experience, I found the rear tires stuck pretty well during
cornering, but the front tires, being on the soft side for the weight
they're carrying tend to scrub off speed during faster cornering as the
sidewalls sort of roll under. This is known as "understeering." You're
turning the steering wheel a fixed amount, but the car isn't fully
responding near the limits of adhesion.
For most drivers, this is safer.
All one needs to do to regain control, is to ease up on the gas, which
is a normal reaction. When the car slows down, the grip at the front
tires improves.
When I learned to drive, cars were all rear wheel drive, and if you
stepped on the gas during cornering, the rear tires would start to
slide to the side.
This can be dangerous if you're not familiar with "turning into the
direction" of the slide. Seems the normal reaction is to turn the wheel
the other way and cause the car to spin out.
So if you increase the pressure in the front tires, you will decrease
understeering.
In my experience, the effect isn't enough to create oversteering - the
rear tires still stick, but the front tires stick better - less
scuffing through turns, which I found quite disconcerting.
A few more pounds pressure in the front tires is also going to make the
ride more harsh.
The factory recommendation for my older Camry with 14" wheels, is 26
psi front and rear, with an optional setting of 29 psi front and rear
for all allowable loads. At 26 you're good for 1-4 passengers, but no
luggage. So I run the optional 29, plus one extra pound up front,
because I still like a smooth ride, and the base 26 psi in the rear.
Seems to work just right. Ride is not too harsh, with a good balance of
handling and fuel economy.
You can also take the total weight of the car, roughly 60% tends to be
in the front, divide by two, so you get the weight on one tire, and
then read your tire sidewall to determine how much load is designed to
be carried at a specific tire pressure, and adjust accordingly.

"Travis Jordan" <no.one@no.net> wrote:
[color=blue]
>Rod wrote:[color=green]
>> Since the front wheel drive Corollas (I have a 2005) have the reverse
>> situation, would it make sense to reduce the rear tire pressures a few
>> psi less than the front, especially if the car is normally used with
>> just the driver? I'd also be interested in your thoughts on handling
>> effects if this were done.[/color]
>
>Use the car manufacturer's recommendations for tire pressure.
>[/color]
And everything else too...
--

-Gord.
(use gordon in email)

Richard wrote:[color=blue]
> "Travis Jordan" <no.one@no.net> wrote in message
> news:6H1Ud.3182677$B07.503662@news.easynews.com...[color=green]
>> Rod wrote:[color=darkred]
>>> Since the front wheel drive Corollas (I have a 2005) have the
>>> reverse situation, would it make sense to reduce the rear tire
>>> pressures a few psi less than the front, especially if the car is
>>> normally used with just the driver? I'd also be interested in your
>>> thoughts on
>>> handling effects if this were done.[/color]
>>[/color]
>
> The effect of dropping the rear pressure relative to the front is to
> promote under-steer. This is a characteristic you car already has to
> excess.
> Richard.[/color]

Richard. While I agree with you regarding lower inflation recommendations
made to increase understeer, the current generation Corollas do NOT
understeer at the recommended pressures even with the OEM Goodyear tires as
you suggest. There is also an unprecedented amount of body roll stiffness
now.
--

- Philip

Richard. While I agree with you regarding lower inflation recommendations
made to increase understeer, the current generation Corollas do NOT
understeer at the recommended pressures even with the OEM Goodyear tires as
you suggest. There is also an unprecedented amount of body roll stiffness
now.[color=blue]
> --
>
> - Philip[/color]
While modern well tuned front wheel drive cars somewhat neutral, when driven
hard into a turn almost all are tuned to understeer. If you lower the rear
pressure or increase the roll stiffness of the front sway bar or increase
the front pressure, you will enhance this characteristic. If anything, with
a modern well tuned front wheel drive vehicle, you might benefit from
increased rear pressure or increased rear roll stiffness, but then you had
better be skilled enough to deal with oversteer at the limits, a good thing
in the hands of an experienced skilled driver on dry roads.

Richard.

Richard wrote:[color=blue]
> Richard. While I agree with you regarding lower inflation
> recommendations made to increase understeer, the current generation
> Corollas do NOT understeer at the recommended pressures even with the
> OEM Goodyear tires as you suggest. There is also an unprecedented
> amount of body roll stiffness now.[color=green]
>> --
>>
>> - Philip[/color]
> While modern well tuned front wheel drive cars somewhat neutral, when
> driven hard into a turn almost all are tuned to understeer. If you
> lower the rear pressure or increase the roll stiffness of the front
> sway bar or increase the front pressure, you will enhance this
> characteristic. If anything, with a modern well tuned front wheel
> drive vehicle, you might benefit from increased rear pressure or
> increased rear roll stiffness, but then you had better be skilled
> enough to deal with oversteer at the limits, a good thing in the
> hands of an experienced skilled driver on dry roads.
>
> Richard.[/color]

This is all about a *Corolla*. Of course it's designed to understeer
heavily. Can anyone imagine Toyota designing a mainstream grocery getter
that exhibits neutral and/or oversteer tendencies? Get real! Philip, we know
you think you've got some kind of racing machine on your hands but you don't
and the XRS is only maginally better.

Richard wrote:[color=blue]
> Richard. While I agree with you regarding lower inflation
> recommendations made to increase understeer, the current generation
> Corollas do NOT understeer at the recommended pressures even with the
> OEM Goodyear tires as you suggest. There is also an unprecedented
> amount of body roll stiffness now.[color=green]
>> --
>>
>> - Philip[/color]
>
> While modern well tuned front wheel drive cars somewhat neutral, when
> driven hard into a turn almost all are tuned to understeer. If you
> lower the rear pressure or increase the roll stiffness of the front
> sway bar or increase the front pressure, you will enhance this
> characteristic. If anything, with a modern well tuned front wheel
> drive vehicle, you might benefit from increased rear pressure or
> increased rear roll stiffness, but then you had better be skilled
> enough to deal with oversteer at the limits, a good thing in the
> hands of an experienced skilled driver on dry roads.
> Richard.[/color]

Stay focused Richard. The only car in discussion is the current generation
Corolla ... which in numerous respects is unlike previous generations in the
area of suspension. This one departs from previous versions in that what
little understeer there is, is built into the OEM tire choice instead of the
steering geometry.
--

- Philip

FanJet wrote:[color=blue]
> Richard wrote:[color=green]
>> Richard. While I agree with you regarding lower inflation
>> recommendations made to increase understeer, the current generation
>> Corollas do NOT understeer at the recommended pressures even with the
>> OEM Goodyear tires as you suggest. There is also an unprecedented
>> amount of body roll stiffness now.[color=darkred]
>>> --
>>>
>>> - Philip[/color]
>> While modern well tuned front wheel drive cars somewhat neutral, when
>> driven hard into a turn almost all are tuned to understeer. If you
>> lower the rear pressure or increase the roll stiffness of the front
>> sway bar or increase the front pressure, you will enhance this
>> characteristic. If anything, with a modern well tuned front wheel
>> drive vehicle, you might benefit from increased rear pressure or
>> increased rear roll stiffness, but then you had better be skilled
>> enough to deal with oversteer at the limits, a good thing in the
>> hands of an experienced skilled driver on dry roads.
>>
>> Richard.[/color]
>
> This is all about a *Corolla*. Of course it's designed to understeer
> heavily.[/color]
snip

You are wrong about the current Corolla, "Fanny." Quite a departure from
the past.
--

- Philip

Philip wrote:[color=blue]
> FanJet wrote:[color=green]
>> Richard wrote:[color=darkred]
>>> Richard. While I agree with you regarding lower inflation
>>> recommendations made to increase understeer, the current generation
>>> Corollas do NOT understeer at the recommended pressures even with
>>> the OEM Goodyear tires as you suggest. There is also an
>>> unprecedented amount of body roll stiffness now.
>>>> --
>>>>
>>>> - Philip
>>> While modern well tuned front wheel drive cars somewhat neutral,
>>> when driven hard into a turn almost all are tuned to understeer. If
>>> you lower the rear pressure or increase the roll stiffness of the
>>> front sway bar or increase the front pressure, you will enhance this
>>> characteristic. If anything, with a modern well tuned front wheel
>>> drive vehicle, you might benefit from increased rear pressure or
>>> increased rear roll stiffness, but then you had better be skilled
>>> enough to deal with oversteer at the limits, a good thing in the
>>> hands of an experienced skilled driver on dry roads.
>>>
>>> Richard.[/color]
>>
>> This is all about a *Corolla*. Of course it's designed to understeer
>> heavily.[/color]
> snip
>
> You are wrong about the current Corolla, "Fanny." Quite a departure
> from the past.[/color]


Put your glasses on - it's FanJet. You're right though, past generation
Corollas had 4 wheel independent suspension instead of the current cheap and
hoppy "twist beam" rear. However, *both* understeer heavily and at the limit
simply push 'n scrub the front tyres. The XRS isn't much better in the
handling department and with the lame gear ratios, isn't much more fun at
all. Have you really _driven_ one of these things lately?

On Sat, 26 Feb 2005 08:43:40 -0600, Rod <nobody@home.com> wrote:

snip[color=blue]
>
>Since the front wheel drive Corollas (I have a 2005) have the reverse
>situation, would it make sense to reduce the rear tire pressures a few
>psi less than the front, especially if the car is normally used with
>just the driver? I'd also be interested in your thoughts on handling
>effects if this were done.[/color]

Many thanks for all the informative responses. Here's how I
summarized them:

Richard said decreasing rear pressure with respect to the front would
increase any tendency to understeer. Philip agreed, but said
current generation Corollas do not understeer except possibly from OEM
Goodyear tire effects. FanJet says Corolla is designed to understeer
heavily; Philip repeated not so for this generation (I do not find
heavy understeer to be the case with my 2005). Gord said leave it
alone. NoSpamPls said roughly 60% of the weight tends to be in the
front, which means that the front tires carry a 50% greater load than
the rear tires (1569 vs. 1046). NSP suggested raising the front tire
pressure to compensate for the additional load. This would also
lower the tendency of the front tires to roll out in hard turns and
thus reduce any understeer.

Yesterday I set the rear tires on the recommended 30 psi and brought
the front to 35 psi. Handling improved markedly in normal and sharp
turns, although I did not wring it out (no place to do that). Steering
effort also decreased noticeably making the car more pleasant to
drive. I might drop back slowly on the fronts so as not to create
tire wear problems. I'm also going to try this on my two other FWD
vehicles.

I'm a happy camper now; thanks very much.

If I misquoted or mis-understood anyone or screwed up the summary feel
free to raise hell with me. I'll probably get chastised anyway just
for summarizing what was already said, but it helped my thinking.

Rod

"Rod" <nobody@home.com> wrote in message
news:4u1121hml82356g2qj4r8ou7ne4q2jj1us@4ax.com...[color=blue]
>I had a 1963 VW Beetle which I kept for 23 years. Tire pressures for
> the VW were different front to back because of the weight of the
> engine plus transaxel on the rear tires. If I remember correctly -
> which I probably don't - they were something like 25 or 30 psi in the
> rear and 15 psi in the front.
>
> Since the front wheel drive Corollas (I have a 2005) have the reverse
> situation, would it make sense to reduce the rear tire pressures a few
> psi less than the front, especially if the car is normally used with
> just the driver? I'd also be interested in your thoughts on handling
> effects if this were done.
>
> Rod[/color]

I have driven a '62 Corvair with the same arrangement and I now own a '93
Corolla.

Part of the reason for the differing tire pressures was relieved in 1968 on
the VW. Part of the handling problem was the fact that the rear axle was
smaller than the front, a problem the Corvair also suffered from. In 1968,
this was changed in the VW, and other guys used to use spacers on the rear
wheels to achieve the same fix. If you make the rear axle slightly wider
than the front, instead of slightly smaller, it has an effect on the
handling geometry.

The '93, on the other hand, has benefited from that little lesson in
geometry. Tire pressure should be nearly equal on all four wheels. Also,
the weight distribution is somewhat more equal, the Corolla isn't as
nose-heavy as some other FWD vehicles. We have an S curve near where I live
that is posted 15 mph. We've taken a fine American car around that curve
and at 15 mph, the front was so nose-heavy, that even with 4 passengers, the
rear began to 'hop'. The Corolla (and between the various family members,
we currently own 3 of them.) suffers no such problem, it's almost like it's
on rails.

Charles of Kankakee

Yesterday I set the rear tires on the recommended 30 psi and brought[color=blue]
> the front to 35 psi. Handling improved markedly in normal and sharp
> turns, although I did not wring it out (no place to do that). Steering
> effort also decreased noticeably making the car more pleasant to
> drive. I might drop back slowly on the fronts so as not to create
> tire wear problems. I'm also going to try this on my two other FWD
> vehicles.
>
> I'm a happy camper now; thanks very much.
>
> If I misquoted or mis-understood anyone or screwed up the summary feel
> free to raise hell with me. I'll probably get chastised anyway just
> for summarizing what was already said, but it helped my thinking.
>
> Rod[/color]

Rod; you need to take it out to a wet track and take it to the limits on
sharp, avoidance turns and see if you can actually control the car with such
a radical change in air pressure. The design criteria for the vender is
neutral handling under normal driving situations and a tendency toward
understeer at the limits under had to control situations. It would be
interesting to hear what you experience as the car approaches and exceeds
its limits.

Richard.

[email]nobody@home.com[/email] (Rod)
wrote:

snip
[color=blue]
>If I misquoted or mis-understood anyone
>or screwed up the summary feel free to
>raise hell with me. I'll probably get
>chastised anyway just for summarizing
>what was already said, but it helped my
>thinking.[/color]

Heh, it entertained me, so thank you!

FanJet wrote:[color=blue]
> Philip wrote:[color=green]
>> FanJet wrote:[color=darkred]
>>> Richard wrote:
>>>> Richard. While I agree with you regarding lower inflation
>>>> recommendations made to increase understeer, the current
>>>> generation Corollas do NOT understeer at the recommended pressures
>>>> even with
>>>> the OEM Goodyear tires as you suggest. There is also an
>>>> unprecedented amount of body roll stiffness now.
>>>>> --
>>>>>
>>>>> - Philip
>>>> While modern well tuned front wheel drive cars somewhat neutral,
>>>> when driven hard into a turn almost all are tuned to understeer. If
>>>> you lower the rear pressure or increase the roll stiffness of the
>>>> front sway bar or increase the front pressure, you will enhance
>>>> this characteristic. If anything, with a modern well tuned front
>>>> wheel
>>>> drive vehicle, you might benefit from increased rear pressure or
>>>> increased rear roll stiffness, but then you had better be skilled
>>>> enough to deal with oversteer at the limits, a good thing in the
>>>> hands of an experienced skilled driver on dry roads.
>>>>
>>>> Richard.
>>>
>>> This is all about a *Corolla*. Of course it's designed to understeer
>>> heavily.[/color]
>> snip
>>
>> You are wrong about the current Corolla, "Fanny." Quite a departure
>> from the past.[/color]
>
>
> Put your glasses on - it's FanJet.[/color]

Fan Jet: One who passes LOTS of heated gasses. ;-)
[color=blue]
> You're right though, past
> generation Corollas had 4 wheel independent suspension instead of the
> current cheap and hoppy "twist beam" rear. However, *both* understeer
> heavily and at the limit simply push 'n scrub the front tyres.[/color]

Nope. Disagree. The level of understeer has been decreased with the
redesigned (value engineered) rear suspension and the move from 14" to 15"
wheels fitted with lower profile tires is much less than earlier. That is
all I have been communicating to you.
[color=blue]
> The
> XRS isn't much better in the handling department and with the lame
> gear ratios, isn't much more fun at all. Have you really _driven_ one
> of these things lately?[/color]

Look ... I OWN a 2003 and have rolled up 43k miles on it. I also travel from
San Bernardino to Big Bear (CA) one to four times a month. The trip starts
off at 800' and has an 8,900' pass over a distance of 36 miles. Now ask me
that question again. Before buying, I drove both stick and automatic
equipped Corollas. The automatic's ratio spacing seemed better suited to
the engine than the stick's. Furthermore the shifter mechanism's slightly
diagonal pattern and feel was NOT to my liking at all. Too easy to misshift
just like the Celica.
--

- Philip