How Big Is Big 17,18,19???

[trevorbrady]

surely there comes a point where too large a contact patch equals lower pressure equals less grip?

Like the caterpillar earth movers are hugely heavy, but because of their large contact patch with the ground, they don't sink.

If the weight of a beetle remains constant but you play around with tyre widths, then a narrower width tyre equals a smaller contact patch equals greater pressure per square foot/metre of that contact patch equals greater friction (grip)

or am I taking it to extremes?