Answer
$6.4\times 10^{-4}m^2$
Work Step by Step
We can determine the required area as follows:
$\Delta P=\frac{F}{A}$
We plug in the known values to obtain:
$690\times 10^3=\frac{90\times 9.8}{A}$
This can be rearranged as:
$A=\frac{90\times 9.8}{690\times 10^3}$
This simplifies to:
$A=1.28\times 10^{-3}m^2$
This the area of contact of two tires, The area of contact of one tire is $\frac{1.28\times 10^{-3}m^2}{2}=6.4\times 10^{-4}m^2$
