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, gaining 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, and 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.

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| Charles Lasitter | Mailing / Shipping |
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You know if you spent your time trying to find a vaccine for AIDS or
something we would probably have a cure by now.

If you were racing at Indy or something you would obviously have some good
insight here. But since your on the roads that we drive on everyday your
calculations don't make a damn bit of difference. You have a Honda with a 4
cyl at that. You do not have a race car. You do not have a high
performance vehicle. You do however have a delusional sense of what your
car is.

Just put the damn tires and wheels on it that you like.

 

I second the motion of the honourable member.

My god man, how much time have you wasted on these useless calculations? If
you want to cut down on more weight, take the seats out and the glove
compartment cover off. Get rid of the stereo and anything you have in the
trunk. Remove the interior door panels. Don't fill the fuel tank up, just
put in the bare minimum you need to get from one gas station to the next one
and you've saved a lot of weight.

Brian

 

I didn't see autox.honda in the group name. Is that in the FAQ
somewhere. Is there FAQ?

"your"? Could you mean "you are" or even "you're"?

Wow. You can't seem to read either. Every time I have asked a
question about the car, I have emphasized that I am looking for
marginal adjustments in various areas that are cumulative.

I will. And do us all a favor. Just put me in your "plonk" file and
ignore my posts if they annoy you. I don't plan to go away.

-- CL.

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

 

I've relied entirely on the calculations of others, who have posted
them all over the internet. What I HAVE done is take note of those
calculations and opinions, and handed them over to other Honda owners
to see if their experiences match up with them or not.

Wow. All my posts have been about unsprung weight and rotational
mass, and now you come back with this garbage on SPRUNG weight.
I happen to like those other parts right where they are.

So if you don't like the fact that I love my new car and want to
enhance it's performance without completely changing it's character,
that's fine. Just follow the same *plonk* advice I've given to the
other "honourable member".

-- CL.

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

 

Consider it done.

 

"Charles Lasitter" wrote

its performance, not it's performance. It's = it is. Thus your sentence
would read "...want to enhance it is performance."

 

Definetly get some lightweight wheels and as far as tires get the goodyears
if they will last a long time. You'll be giving up weight by mounting them
on lightweight rims. I have some Konig rims on my Civic that have the weight
molded on the outer part of the rim. It's 635kg. which is about 13lbs.
pretty light. I recommend Konig for your wheels theyre well balanced and
precision made.



-Jeff

 

I have never really thought of the differences
between sprung and unsprung weight. What is the
effect (other than when I take fast corners and
it moves to the other side of the trunk) of
carrying a 50-70lb tool box in the trunk?

t

 

635 kg = 77 lb

 

you two crack me up. tell me again, /how/ many pounds to the kilogram?
this is an all-metric honda n.g. & we need a laugh.

 

How is it an 'all metric honda ng'? I use Imperial measurements for my daily
usage, always have and always will. I was just pointing out his lack of a
decimal point.

Brian

 

635 kg * 2.2 lbs/kg = 1397 lbs. (TI-55 calculator converts it to 1399.9)
Truly light-weight, hi-performance wheels!
"Alf, would you bring the crane and help me get this wheel off?"


Tom Willmon
near Mountainair, (mid) New Mexico, USA

Ya sai it won't fit? Blimey, Alf, get a bigger 'ammer!

Net-Tamer V 1.12.0 - Registered

 

You caught me!

-- CL.

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

 

Boy, this takes me back to the 60s....

Ride and suspension conformance to the road surface both improve as the
ratio of sprung to unsprung weight increases. Within the load limits of the
suspension, more weight in the trunk smooths the ride and helps hold the
tires on the pavement over bumps. Think of it as: the road makes your wheels
bounce and your wheels make your car bounce. The lighter the wheels the
poorer the energy transfer from the road interface to the car.

The emphasis on the unsprung weight is that it is easier to make a
difference, at least starting with stock. Aggressive selection of wheels and
tires can reduce unsprung weight by 50%. Increasing the sprung weight 100%
(same doubling of the ratio) is not likely to improve your handling and
ride! 60 lbs in a 3000 lb car is 2% difference, so the tool box won't make
the Honda ride like a Cadillac.

Bicycling enthusiasts are even more rabid, since spinning the wheel mass up
takes some leg power. The mantra is "an ounce on the wheel is worth a pound
on the frame." I don't know just how true that is, but you get the idea.

Mike

 

"Charles Lasitter" wrote

Ah - I was worried about you -- you DO have a sense of humor!

 

thanks mike.

 

Theyre 13lbs. 77lbs would weigh a ton on a honda civic..theyre lightweight.

 

Wow. From all the other physics discussions I've read, I can only
say "it depends".

http://tinyurl.com/9yuqu

A lighter wheel has less mass when it bounces and if it was not
opposed by the springs or dampeners, yes, it would bounce more, and
that would be bad from many standpoints.

But the springs oppose this action, and they don't have to compress
as much to do so with a lighter wheel.

Now ideally ALL the components of a suspension system should be
matched and tuned. The spring rate and shocks would match the tires,
which would match the style of driving, the vehicle load, and so on.
There's nothing about it that's cut and dried as far as I can tell.

Rotational mass can be very important, and it all depends on where
you start. Bicycle riders don't produce much torque compared to a
four cylinder engine, and so they're right to be rabid about it.

Four cylinder engines generally don't produce the torque of six or
eight cylinder engines, and so rotational mass makes more of a
difference.

Miata owners are very keen to control and reduce the weights of their
wheels because their cars are light and by all their accounts the
difference will be quite large.

In a few weeks I hope to have some lighter wheels on my 4Cyl LX, and
then I'll know for sure whether it makes any difference, at least for
me.

-- CL.

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