Fuchs Wheel Data and Tires

[Mills911C3]

You can' t compare sedans and F1 cars in most areas they are just different animals that share only a superficial similarity, specific to the discussion here is a series regulated by arbitrary rules compared to a series production sedan limited only by cost, space and availability constraints

wrt to wheels and tires

wheels:
wheel mass specs are all over the place, there are 17s and 18s of the same or larger width that weigh less than some 16s, for instance fuchs 8x16 that I weighed came in at ~19# and Fikse 8x17 @ ~16#,
yes in general and theoretically 15s are the lightest and 18s the heaviest and 7s are lighter than 9s but there are exceptions.. It's really not that critical though as the ranges are relatively small and overlapping and the effects of a few extra #s are far less important than the effects of tire OD and tire weight, the reason is that most of the wheel mass is concentrated more toward the axle while most of a tires weight is concentrated at the outer edge,

tires:
the tire OD is a double edged sword, inertial costs come in 2 forms, linear and rotational, linear is straightforward and OD doesn't affect it, but for rotational costs the radius is squared, additionally extra OD adds to gearing cost which are multiples of the rest of the gearing, Both of these factors mean that small increases or decreases in tire OD lead to outsize changes in torque available for acceleration

Obviously you want to minimize all extra mass, paying particular attention to rotating and unsprung mass as it has additional implications for performance, but the more critical thing to minimize is Tire OD and weight

Here's one example
A stock 7 & 8 x16 Fuchs 16" setup compared to an efficient 17, The 17s aren't even the lightest available, Tires lines are the same A052s using factory specs for weight. the key thing here is the relative shortness of the 17s, which net around 2 lb-ft extra torque despite ~1 lb-ft greater inertial cost because of the gains in gearing costs, you net ~2lb-ft more torque available for acceleration, As a bonus the 17s have the potential to develop significantly more grip because of the geometry of the tire/wheel unit


The 16s can be improved by a judicious tire choice

Here the same stock 7 & 8 x16 Fuchs are on both set ups, but shorter 205/50 & 225/45s are used in the second set, here the shorter tires are also lighter and there is a net gain of ~5 lb-ft

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