[s-cars] Re: Tires/Wheels

[William Noland]

Ah, the great wheel/tire debate. Lower unsprung weight is obviously a
good thing. Less weight means the wheel/tire will accelerate more
quickly and stay in better contact with the road for better handling.
OTOH, lower weight means:

1) A smaller wheel/taller sidewall combo (rubber is lighter than metal).
The taller sidewall, though, will tend to deflect more than a shorter
one, which results in less crisp handling and a tendency for the
footprint to deform somewhat = less rubber on the road.

2) An ultra light, larger wheel/short sidewall combo -- normally coupled
with a wider tire. Great for turn in and handling. Downside? Ultra light
wheels tend to be less strong, which translates to a potential for bent
wheels in the real world of pothole infested streets. BTDT. And, did I
mention higher cost for the wheels and tires?

Footprints -- Skinnier/higher profile tires tend to have a longer,
skinnier contact patch. Wider, low profile tires have a shorter, wider
contact patch. Longer and skinnier contact patch means better
longitudinal grip for moving off on slippery surfaces. Check out snow or
dirt/gravel tires on World Rally cars. They're almost comically skinny.
I have wider tires on the rear of my motorcycles. Then check out tarmac
tires on the rally cars -- more along the lines of your low profile,
wider roadracing tires. The wider footprint gives greater latitudinal
grip for going round the corners. So, keep your snow tires tall and
skinny and your summer tires short and fat.

A pretty comprehensive listing of wheel weights can be found at
http://www.wheelweights.net/. Many of the tire manufacturers' websites
list weights of their various tires -- Toyo and Dunlop for sure. (Toyo
T1-S is probably the lightest tire for a given size you'll find. Superb
in the wet and excellent in the dry, too.)

Bill N

>You know guys, I've been thinking about this whole tire/wheel obsession
>that everyone seemingly has, and I have a few questions and a few
>statements.
>
>1. It is given fact that the lower the unsprung weight, the better the
>handling and performance. Among other things, lower unsprung weight
>means that the wheel returns contact the ground faster after moving
>over anything that causes it to move upward. This translates into
>serious value for potholes, snow and poor-/off-road surfaces.
>
>2. Conversely, the bigger the footprint of the tire, the better
>traction is established any moment of contact if the read/tire
>interface is clean (in snow, rain, a smaller footprint exerts more
>force on the area and therefore helps move away or crush the
>interference agent). This is in general relevant only in situations of
>high traction requirements (high speed turns, very hard acceleration,
>extreme braking).
>
>Traditionally, then, for dry weather driving, the ideal would be to get
>as light a tire/wheel combination as possible with as big a footprint
>as possible (within reason). Now comes the question(s):
>
>A) How come wheel manufacturers rarely place the weight (mass) of their
>wheels in their listings, and no one on the list ever makes any
>comments about the weight of their wheels? Ditto for tires...
>
>B) Why do you all automatically assume bigger is better (since bigger
>usually means more weight... "More Weight!" cried Giles Corey)?
>
>Just some little thoughts... anything better than another tirade by the
>list's incoherent childish member(s)...
>
>Cheers!
>=-= Marc Glasgow
>
>
>
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