Xeno wrote: "
At a given tyre pressure and vehicle mass, the wide and narrow tyres
will have the same contact patch area. So no gain there. What does
happen is that the contact patch becomes wider. A wide contact patch
provides adequate cornering force at smaller slip angles but they reduce
self aligning torque because of the reduced pneumatic trail. Therefore
natural stbility and steering feel is commensurately reduced. There is a
practical width of tyre for every vehicle but *cosmetic appearance*
trumps this so people want the look of wider low profile tyres. There is
also a section profile that is optimum for both ride comfort and
handling allowing the tyre to form part of the *springing*. IIRC, this
was about 70. at a section of 65, the ride gets more harsh and continues
to do so the lower the section profile gets. "

Agreed, and makes perfect sense!

I'd say the lowest profile I'd go for is 65-series.

Even if the contact patch for, say, a 70 and a 40
series tire is approx. the same area, that patch should
be parallel, not perpendicular, to direction of travel.
That should be common sense, and flies in the face
of all the aftermarket modders who want to throw
40-series bling 20" rims on a '85 Caprice or some such
that was specifically engineered to work with 70-75-
series tires and a specific rim diameter(typically 15 or
16") and width.

By the way, the Sonata I drove that 'steered itself'
exacerbated matters due to its 55-series tires on
17" rims - a Limited. Thing had a reasonable steering
heft, yet somehow felt like driving on ICE, even on a
dry highway on a sunny day. The steering wheel would
slowly start tuggin to one side, and I'd start applying
counter forcd, and then the steering wheel would snap
quickly too far thr other way, causing the wander. It
was a 'sticky' feeling, sort of.


I wish I'd kept the car, and just had gone to the dealer
to minus-size down to 60 or 65series tires on 16 or
15" rims. Combined with the reduced-assist Sport mode,
the 'ghost' in the EPS would have been even less of an
issue.