Handling/Ride: +Rubber/-Unsprung weight?

I'm already excited about the prospect of new alloys that will shave
seven pounds off the corners, or a pound or two less depending on the
plus sizing factor.

Now I'm seeking advice about diminishing marginal returns as regards
more rubber on the road versus further reducing unsprung weight.

My '05 Accord LX 4Cyl 5M came with Michelin's "CAFE" tires, good for
fuel economy but not much else, scoring in the bottom half of most
everything in Performance All-Season category. But they are already
fairly light for 205/65 HR15 92H tires, at 21 pounds each.

My challenge is to find the best weight to performace ratio for the
tire. Less unsprung weight means the suspension works better at what
it does, including keeping that tire on the pavement where it can do
some good.

Goodyear TripleTreds score very high marks for ride and noise comfort,
but do they score so well _because_ they're 5# heavier per tire? I
probably wouldn't pay that price if I could have a pretty good ride in
a less beefy tire.

It's easy enough to improve the wet and dry traction with better
compounds. Improving handling and steering response can be done by
brand selection, but sometimes it means reducing the aspect ratio.

One challenge I face is figuring out how much of (handling/ride) to buy
just by switching tire makers at the same size. Some tire makers score
dramatically better than others in Tire Rack's ratings, such that just
by switching makers, you gain improvements in both areas at the same
time. (But switching to the top rated Turanza tire in the same
category adds four pounds!)

Then again it's possible to make improvements in one area by trading
off against another. The examples below adjust unsprung weight changes
for plus sizing.

With example (2) below (Kumho ECSTA HP4 716s), I can get 8/10" more
rubber at the OE TIRE weight, while cutting the sidewall by 6/10".

Matching the stock tire exactly with option (1) would mean giving back
two pounds in exchange for across the board preformance by changing
brands.

With option (3) you drop one more NET pound, putting you eight pounds
lighter overall

22# Steelies + 21# OE Tire = 43# W+Tire

------------------->S+W/DIFF/Sect Width
1) 205/65 HR15 92H---38--5---8.1"
2) 215/55 HR16 91H---36--7---8.9"
3) 205/55 HR16 89H---35--8---8.4"
4) 205/60 HR16 91H---36--7---8.2"

(16x7 alloys are a pound heavier than 15x7)

If they all satisfied your +/- 3% speedo, and the speed rating was OK
and the load rating didn't matter, which would you pick for:

Steering response / Handling / Turn-in?
Ride comfort?
Throttle response / acceleration?
Fuel economy?

Seems to me that the 19#/8.4" section width might be the sweet spot --
but that depends on the diminishing returns theory of rubber on the
road vs unsprung weight! (The 65/60/55 differences are probably mild
enough to be inoffensive.)

Thanks for your thoughts on this.

-- CL.

+-----------------------------------------+
| Charles Lasitter | Mailing / Shipping |
| 401/728-1987 | 14 Cooke St |
| cl+at+ncdm+dot+com | Pawtucket RI 02860 |
+-----------------------------------------+

On Tue, 12 Apr 2005 16:12:11 GMT, Charles Lasitter
> wrote:

>I'm already excited about the prospect of new alloys that will shave
>seven pounds off the corners, or a pound or two less depending on the
>plus sizing factor.
>
>Now I'm seeking advice about diminishing marginal returns as regards
>more rubber on the road versus further reducing unsprung weight.

What for? Are you after good handling while going sideways through
corners on bumpy roads? Unsprung weight is important if you're racing
on bumpy tracks or rallying in the boondocks. Otherwise chasing after
every last pound is hardly worth it.

Anyhow, if minimum unsprung weight is a real necessity, go find some
magnesium wheels and never mind the tires.

John Ings > wrote in
:

> What for? Are you after good handling while going sideways through
> corners on bumpy roads?

In Providence, Rhode Island, it's the interstates at 70mph ...

> Unsprung weight is important if you're racing on bumpy tracks or
> rallying in the boondocks. Otherwise chasing after every last
> pound is hardly worth it.

Is that why Honda did backflips to reduce rotational mass everywhere
it could in the S2000?

I've read elsewhere that reductions in rotational mass play out as
more "apparent" horsepower. I don't pretend to know myself, that's
why I ask here, politely.

> Anyhow, if minimum unsprung weight is a real necessity, go find
> some magnesium wheels and never mind the tires.

I understand that you should be ready to clean and polish them every
day, too.

I'd ask you again to FOCUS ON THE QUESTION: Diminishing returns in
unsprung weight, rotational mass, ride and handling.

The question is one of where and when additional investments in one
area don't generate payoffs that would be more easily attained
elsewhere.

-- CL.

+-----------------------------------------+
| Charles Lasitter | Mailing / Shipping |
| 401/728-1987 | 14 Cooke St |
| Pawtucket RI 02860 | cl+at+ncdm+dot+com |
+-----------------------------------------+

On Tue, 12 Apr 2005 22:59:42 GMT, Charles Lasitter
> wrote:

>> What for? Are you after good handling while going sideways through
>> corners on bumpy roads?
>
>In Providence, Rhode Island, it's the interstates at 70mph ...

Unless you're cornering hard at that speed, unsprung weight won't
count for much.

>> Unsprung weight is important if you're racing on bumpy tracks or
>> rallying in the boondocks. Otherwise chasing after every last
>> pound is hardly worth it.
>
>Is that why Honda did backflips to reduce rotational mass everywhere
>it could in the S2000?

Sure, but they can actually make really significant reductions. Not
just a pound or so, but real weight reduction that only a factory can
manage by careful design.

>I've read elsewhere that reductions in rotational mass play out as
>more "apparent" horsepower. I don't pretend to know myself, that's
>why I ask here, politely.

Yes, that's true, but again, you're not going to notice a pound less.

>> Anyhow, if minimum unsprung weight is a real necessity, go find
>> some magnesium wheels and never mind the tires.
>
>I understand that you should be ready to clean and polish them every
>day, too.

Yes, real mag wheels are a race track thing. They can't stand up to
road salt at all for instance.

>I'd ask you again to FOCUS ON THE QUESTION: Diminishing returns in
>unsprung weight, rotational mass, ride and handling.

You're way out on the tapering end of that diminishing return.

>The question is one of where and when additional investments in one
>area don't generate payoffs that would be more easily attained
>elsewhere.

That's precisely where you're at.

John Ings > wrote in
:

>>Is that why Honda did backflips to reduce rotational mass
>>everywhere it could in the S2000?

> Sure, but they can actually make really significant reductions.
> Not just a pound or so, but real weight reduction that only a
> factory can manage by careful design.

I think that seven pounds per corner tire+wheel is REAL weight
reduction. Nine pounds would be even more real. My only real
question is whether that last two pounds might be better invested in
+1 wheels and more rubber on the road.

>>I've read elsewhere that reductions in rotational mass play out as
>>more "apparent" horsepower. I don't pretend to know myself,
>>that's why I ask here, politely.

> Yes, that's true, but again, you're not going to notice a pound
> less.

Not noticing a an additional pound at the margin tells me something.
Not noticing an extra two pounds at the margin tells me something.

>>> Anyhow, if minimum unsprung weight is a real necessity, go find
>>> some magnesium wheels and never mind the tires.

I've observed up to five pounds difference in tires of the same size
spec. I don't think that's nothing. I think I might notice.


>>I'd ask you again to FOCUS ON THE QUESTION: Diminishing returns in
>>unsprung weight, rotational mass, ride and handling.

> You're way out on the tapering end of that diminishing return.

Thank you. This is what I suspected, and needed to know.

>>The question is one of where and when additional investments in one
>>area don't generate payoffs that would be more easily attained
>>elsewhere.

> That's precisely where you're at.

Again, thank you very much for your input.



--
-- CL.

+-----------------------------------------+
| Charles Lasitter | Mailing / Shipping |
| 401/728-1987 | 14 Cooke St |
| cl+at+ncdm+dot+com | Pawtucket RI 02860 |
+-----------------------------------------+

I am curios as to how YOU are going to notice any difference of even 7 lbs
per wheel in a god damned stock Honda Accord with a 4 cyl motor.

If you were geuinely concerned about performance then you wouldn't have
bought a family sedan. Go go a real sports car if that is what your
interested in.



"Charles Lasitter" > wrote in message
...
> John Ings > wrote in
> :
>
>>>Is that why Honda did backflips to reduce rotational mass
>>>everywhere it could in the S2000?
>
>> Sure, but they can actually make really significant reductions.
>> Not just a pound or so, but real weight reduction that only a
>> factory can manage by careful design.
>
> I think that seven pounds per corner tire+wheel is REAL weight
> reduction. Nine pounds would be even more real. My only real
> question is whether that last two pounds might be better invested in
> +1 wheels and more rubber on the road.
>
>>>I've read elsewhere that reductions in rotational mass play out as
>>>more "apparent" horsepower. I don't pretend to know myself,
>>>that's why I ask here, politely.
>
>> Yes, that's true, but again, you're not going to notice a pound
>> less.
>
> Not noticing a an additional pound at the margin tells me something.
> Not noticing an extra two pounds at the margin tells me something.
>
>>>> Anyhow, if minimum unsprung weight is a real necessity, go find
>>>> some magnesium wheels and never mind the tires.
>
> I've observed up to five pounds difference in tires of the same size
> spec. I don't think that's nothing. I think I might notice.
>
>
>>>I'd ask you again to FOCUS ON THE QUESTION: Diminishing returns in
>>>unsprung weight, rotational mass, ride and handling.
>
>> You're way out on the tapering end of that diminishing return.
>
> Thank you. This is what I suspected, and needed to know.
>
>>>The question is one of where and when additional investments in one
>>>area don't generate payoffs that would be more easily attained
>>>elsewhere.
>
>> That's precisely where you're at.
>
> Again, thank you very much for your input.
>
>
>
> --
> -- CL.
>
> +-----------------------------------------+
> | Charles Lasitter | Mailing / Shipping |
> | 401/728-1987 | 14 Cooke St |
> | cl+at+ncdm+dot+com | Pawtucket RI 02860 |
> +-----------------------------------------+

"halo2 guy" > wrote in message
...
>I am curios as to how YOU are going to notice any difference of even 7 lbs
>per wheel in a god damned stock Honda Accord with a 4 cyl motor.
>
> If you were geuinely concerned about performance then you wouldn't have
> bought a family sedan. Go go a real sports car if that is what your
> interested in.

Please explain how the number of cylinders matter.

"halo2 guy" > wrote in
:

> I am curios as to how YOU are going to notice any difference of
> even 7 lbs per wheel in a god damned stock Honda Accord with a 4
> cyl motor.

This rotational mass / moment of inertial is not something I dreamed
up. It's a performance issue of which Honda itself is keenly awa

http://tinyurl.com/4vjgp

"... Honda engineers wanted to keep the S2000 powertrain's entire
rotational mass to a minimum, thereby minimizing inertia, and the
response time between driver input and vehicle reaction."

http://tinyurl.com/4mzwo

"As an added benefit, putting lighter wheels on the car can increase
your engine's apparent power. Why? Well the engine has to turn the
gearbox and driveshafts, and at the end of that, the wheels and tyres.
Heavier wheels and tyres require more torque to get turning, which saps
engine power. Lighter wheels and tyres allow more of the engine's
torque to go into getting you going than spinning the wheels. That's
why sports cars have carbon fibre driveshafts and ultra light alloy
wheels.

> If you were geuinely concerned about performance then you wouldn't
> have bought a family sedan.

I'm very pleased with my purchase. It's a fine car that can
comfortably seat adults, offering a sportier ride than a Toyota Camry,
and I plan to enhance the vehicle's strong points and enjoy owning it
for a very long time.

> Go go a real sports car if that is what your interested in.

And so you are ... Honda's good will ambassador to first time Honda
buyers?

I put a lot of time and effort into composing questions as thoughtfully
as possible, and then posting them in forums where they are most
relevant, and the worst part of process is not the well intentioned
mis-information that is all to common on the internet.

It's jerks like you, who show their ass while offering nothing of
value, not even a meaningful critique of the questions posed that helps
bring relevant issues more clearly into focus.

-- CL.

+-----------------------------------------+
| Charles Lasitter | Mailing / Shipping |
| 401/728-1987 | 14 Cooke St |
| cl+at+ncdm+dot+com | Pawtucket RI 02860 |
+-----------------------------------------+

"Steve Bigelow" > wrote in news:lr-
:

> Please explain how the number of cylinders matter.

It's really about torque. Other things being equal, more cylinders
and more displacement = more torque.

http://tinyurl.com/4mzwo

"As an added benefit, putting lighter wheels on the car can increase
your engine's apparent power. Why? Well the engine has to turn the
gearbox and driveshafts, and at the end of that, the wheels and
tyres.

"Heavier wheels and tyres require more torque to get turning, which
saps engine power. Lighter wheels and tyres allow more of the
engine's torque to go into getting you going than spinning the
wheels. That's why sports cars have carbon fibre driveshafts and
ultra light alloy wheels."

I make no pretense of being any kind of expert, but I've recently
read a lot of information from people that consider themselves to be
experts, and I'm just looking for feedback from this group as to how
things might apply that I've read elsewhere.

-- CL.

+-----------------------------------------+
| Charles Lasitter | Mailing / Shipping |
| 401/728-1987 | 14 Cooke St |
| cl+at+ncdm+dot+com | Pawtucket RI 02860 |
+-----------------------------------------+

Charles Lasitter wrote:
> I make no pretense of being any kind of expert, but I've recently
> read a lot of information from people that consider themselves to be
> experts, and I'm just looking for feedback from this group as to how
> things might apply that I've read elsewhere.

eh, youre doing good. i dont think many of us have really thought about
the weight of tire/wheel combos too much, pertaining to how much extra
power is given and the effects on speedometer readings, etc. you must
work in a technical field, right?

people with civics know if they want a light factory wheel/tire setup,
to get the wheels off an HX. theres no similar "economy" accord, unless
you count the hybrid... does that use the same wheels/tires?