wire wheels another provocation

[C M Smith <cmsmith@xxxxxxxxxxxxxxx>]

My point about wire wheels for automobiles (four wheelers) was precisely 
that they were inadequate from an engineering point of view. Sure they were 
lighter than the equivalent steel wheel but they were unable to deal with 
the side forces generated by really good tires. Pneumatic tires are slip 
angle devices on four wheeled vehicles. As tires got better this became 
obvious. The tire tries to punch the hub out of the wire wheel causing 
endless maintenance problems. Camber thrust vehicles (two wheelers) do not 
suffer from this but do suffer from spoke stretch, hence the movement to 
alloy wheels for two wheeled performance vehicles.

Bicycle and motorcycle wheels exploit the main advantage of wire wheels 
which is of course that the axle is suspended from a wire in tension rather 
than held up by  a pillar in compression ( the spoke is a tension device). 
However, on four wheeled vehicles pneumatic tires generate considerable 
side forces through slip angles making them unsuitable for wire wheels. 
Before pneumatic tires a "tire" (early tires were simply steel bands shrunk 
onto a wooden wheel as a  wear surface and a compression structure, 
probably related to similar structures on wooden barrels) could not 
generate significant side forces. Spokes only needed to be strong enough to 
resist the collision side force of a wheel striking a rut or other solid 
object sideways.

Wire wheels for cars were no doubt aimed at achieving low unsprung weight 
with sufficient strength, together with good brake drum cooling. Alloy 
wheels as well as disc brakes make wire wheels obsolete. Wire wheels are 
simply an anachronism unless installed on the correct period vehicle.

I do not disagree with wire wheels being installed on correct period 
automobiles.

I find installation of wire wheels on non period automobiles to be an 
absurd affectation. I've seen wires on modern Jaguars and Mercedes. This is 
absurd affectation. Thankfully, this is now mostly past. Only to be 
replaced with the more modern affectation of fitting extremely large wheels 
with absurdly low profile tires to everything from rice rockets to SUVs. 
Puleeze.

Extremely low profile tires and large wheels increase unsprung weight, 
reduce grip unless suspension geometry is carefully planned to minimize 
camber changes (usually through extremely limited wheel travel) and 
seriously increase the road hazard risk of blowouts etc. No one in their 
right mind would put anything shorter than a 45 series tire on a modern 
street vehicle. For an SUV, 78 is the minimum appropriate profile. For my 
tastes, 50 series is it for street rubber, 45 is just silly and anything 
shorter is pure affectation enjoyed by the ignoranti.

Cheers


Michael Smith
White 1991 164L
Original owner
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