Originally posted by hornerdon:
there is a point in which that contact patch is "good enough" to handle to cornering ability of the car, and any more is at best a waste, and at worst a detriment.
Don, good observation...the cars were early eighties RX-7 GSLs , the drivers were Paul Kozlak (sp?) and myself, and the tire was the legend in it's own time Yokohama A001R.

OK, so lets recap....

If your rules limit your rim width, you must find and use a tire that is the proper section width for that rim.

Between two tires, the one with the smaller outside diameter will always accelaerate faster, as it's another way of changing the final drive ratio.

On tracks with long straights, the narrower tire with less aero and rolling resistance will be superior if the car is horsepower challenged.

And finally, the issue of "traction" or "stiction" .....If the car is light, going to a 30% larger contact patch will lessen the load the tire sees, (in pounds per square inch), and a subtle effect can occur. Much like a narrower tire gets through the snow better, and a wide flat tire is more likely to hydroplane (on the same vehicle), a lightly loaded tire may not actually have enough load to generate it's maximum cornering grip. keep in mind that a switch to a softer compound should be able to overcome that, but, if such a choice isn't available, perversely, a switch to a smaller tire may make the car faster!

And the point of the tire being a rotating mass is well taken, but if the outside diameter is the same, often the larger rim diameter combination will have superior acceleration deltas, due to it's lighter weight. (Generally, an inch (in dia.) of aluminum wheel is lighter than the same inch of a rubber tire.

In the end, there are so many variables, often conflicting, that actual testing is the way to go. Which brings to the original question....sorry Alan, I've got no first hand Golf wheel choice definative answers!

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Jake Gulick
ITA 57 RX-7
New England Region
[email protected]