Tire Aspect Ratios, High-vs-Low Profile, and Straight-line Stability

Tire Aspect Ratios, High-vs-Low Profile, and Straight-line Stability


Assumptions: Same brand & model of tire, same alignment
settings on test vehicle, same level of power steering assist,
same road test trajectory, same weather conditions, and of
course, same driver. Vehicle's cold tire pressure is maintained,
to within 1psi, of vehicle mfg placard on door pillar, with both
sets of tires.


Differences: 4 High profile(70 series for example) tires are
mounted and driven, then, 4 Low profile(50 series) tires are
mounted and driven. Maintenance, to within 2% of each
other's diameter for speedometer accuracy, is taken into
consideration.


Given the assumptions proscribed in the first paragraph:
With which set of tires, the high-profiles or the lo-profiles,
will the test vehicle..


1. Track truer in a straight-line?

2. Respond quicker to steering inputs?

3. Feel heavier when turning the steering wheel away from center?

3. Return the steering wheel quicker to center from turns?

wrote:
> Tire Aspect Ratios, High-vs-Low Profile, and Straight-line Stability
>
>
> Assumptions: Same brand & model of tire, same alignment
> settings on test vehicle, same level of power steering assist,
> same road test trajectory, same weather conditions, and of
> course, same driver. Vehicle's cold tire pressure is maintained,
> to within 1psi, of vehicle mfg placard on door pillar, with both
> sets of tires.
>
>
> Differences: 4 High profile(70 series for example) tires are
> mounted and driven, then, 4 Low profile(50 series) tires are
> mounted and driven. Maintenance, to within 2% of each
> other's diameter for speedometer accuracy, is taken into
> consideration.
>
>
> Given the assumptions proscribed in the first paragraph:
> With which set of tires, the high-profiles or the lo-profiles,
> will the test vehicle..
>
>
> 1. Track truer in a straight-line?
>
> 2. Respond quicker to steering inputs?
>
> 3. Feel heavier when turning the steering wheel away from center?
>
> 3. Return the steering wheel quicker to center from turns?

I would think that the low profile would fit all of the questions.
Less sidewall = less flex.

Paul in Houston TX wrote:
> wrote:
>> Tire Aspect Ratios, High-vs-Low Profile, and Straight-line Stability
>>
>>
>> Assumptions: Same brand & model of tire, same alignment
>> settings on test vehicle, same level of power steering assist,
>> same road test trajectory, same weather conditions, and of
>> course, same driver. Vehicle's cold tire pressure is maintained,
>> to within 1psi, of vehicle mfg placard on door pillar, with both
>> sets of tires.
>>
>>
>> Differences: 4 High profile(70 series for example) tires are
>> mounted and driven, then, 4 Low profile(50 series) tires are
>> mounted and driven. Maintenance, to within 2% of each
>> other's diameter for speedometer accuracy, is taken into
>> consideration.
>>
>>
>> Given the assumptions proscribed in the first paragraph:
>> With which set of tires, the high-profiles or the lo-profiles,
>> will the test vehicle..
>>
>>
>> 1. Track truer in a straight-line?
>>
>> 2. Respond quicker to steering inputs?
>>
>> 3. Feel heavier when turning the steering wheel away from center?
>>
>> 3. Return the steering wheel quicker to center from turns?
>
> I would think that the low profile would fit all of the questions.
> Less sidewall = less flex.

Yep. But add

Will ride worse.
Will transmit more noise into the vehicle.

In order to keep the same diameter on the same rim size the low profile
will be MUCH wider which can cause interference issues. So plan on going
up at least one size.


--
Steve W.

OK, here are my perceptions based upon what I've
read and observed over the years:


1. Straight line stability: Goes to the skinny, low profile
tire because more weight is concentrated in a narrower
patch.


2. Response to steering inputs: The wide, low profile
tire because patch is wider left to right.


3. Weight build up when turning the wheel: Skinny low
profile tire, for reasons stated in #1.


4. Quicker return from turns: Skinny low profile for
reasons stated in #1.


Think about why stability angles(caster, SAI/kingpin) in factory
wheel alignment specs in cars have increased drastically over 30+
years: From practically zero to two degrees of caster in the 1970s,
to between 4-6deg caster for modern mainstream vehicles.
During anout the same time when 75-series tires began being
replaced by 70-series, and 60-series, and 50 and 40-series(!)


Narrower, high-profile tires of the same overall inflated diameter
track straighter with less caster or kingpin, and in my opinion,
handle accordingly. And are better overall in snow and ice.


So what are low-profiles better for? Appearances! Less
ugly sidewalls, and acres of chrome wheel bling! Wowww!
Oh, and straightline acceleration - which is not a criteria I
consider handling.

wrote:

(snip)
> So what are low-profiles better for? Appearances! Less
> ugly sidewalls, and acres of chrome wheel bling! Wowww!
> Oh, and straightline acceleration - which is not a criteria I
> consider handling.

Ever do any twisty road racing or fast mountain driving?
I was amazed at how much better cars handle with low profiles.
They have less squirm and go where you point the steering wheel now, not where it
was pointed last. They stick to the road and don't peel under the wheels as much.
But for normal driving around Houston, I stick with high profiles.
They are more squishy and less harsh.
Can't get much over 25 mph here anyways.

Paul in Houston Tx wrote: "Ever do any twisty road racing or fast mountain
driving?"

Not a lot, but I do know that wider low profile
respond more readily to steering input - and
to road imperfections. Not so high-profile
tires.

I want to feel resistsnce to turning, in the
form of weight build-up in turns, and a
steering wheel that snaps quickly back to
center from a turn.


Need a lot more caster(or less power steering
boost) with wide tires to accomplish that.

Two weeks ago:

Traded in my 2013 Hyundai Sonata Ltd with 55 series 17"s for
an Elantra with 65 series 15"s. Handling difference is NIGHT
vs DAY! Elantra tracks straighter, heavier steering, better return
from turns. I feel like I'm actually DRIVING again.

Keep your low-profile 17" and wider WAGON WHEELS, I'm
sticking with something that HANDLES.

wrote:
> Two weeks ago:
>
> Traded in my 2013 Hyundai Sonata Ltd with 55 series 17"s for
> an Elantra with 65 series 15"s. Handling difference is NIGHT
> vs DAY! Elantra tracks straighter, heavier steering, better return
> from turns. I feel like I'm actually DRIVING again.
>
> Keep your low-profile 17" and wider WAGON WHEELS, I'm
> sticking with something that HANDLES.

Excellent!

wrote:

> Traded in my 2013 Hyundai Sonata Ltd with 55 series 17"s for
> an Elantra with 65 series 15"s. Handling difference is NIGHT
> vs DAY! Elantra tracks straighter, heavier steering, better return
> from turns. I feel like I'm actually DRIVING again.

You forgot:
4 inch shorter wheelbase
500 lbs less weight
Different rear suspension
Basically a different car.
Likely had an alignment done before you bought it too, compared to
the bashed-into-curbs, no-maintenance thing you turned in.
So of course it's going to handle differently.
Next time try swapping wheels & tires ON THE SAME CAR.

"Sanity Clause" > wrote in news:nst31j$70t$1@dont-
email.me:

>
> wrote:
>
>> Traded in my 2013 Hyundai Sonata Ltd with 55 series 17"s for
>> an Elantra with 65 series 15"s. Handling difference is NIGHT
>> vs DAY! Elantra tracks straighter, heavier steering, better return
>> from turns. I feel like I'm actually DRIVING again.
>
> You forgot:
> 4 inch shorter wheelbase
> 500 lbs less weight
> Different rear suspension
> Basically a different car.
> Likely had an alignment done before you bought it too, compared to
> the bashed-into-curbs, no-maintenance thing you turned in.
> So of course it's going to handle differently.
> Next time try swapping wheels & tires ON THE SAME CAR.
>
>
>

yep I gaurenty all things the same, the wider low profile tires will handle
better, ride rougher but handle better. KB