The first one, anyone know a general volume of a tire on a 15 inch wheel? I know it depends on tire size and the shape of the rim on the inside, but just a general number would be awesome.

The second, to figuer out the loading a-arm would see during normal driving would it just be the force of the spring can provide for general terms? I think the only way an a-arm would see higher loads would be if the spring was bottomed out.

Thanks for your time.

 

volume of torus = 2 * pi^2 * R * r^2
195/55 R 15
take r = average tire section radius
= 7.5cm
take R = radius to centerline of 'tube'
= 24.3cm
V = 27000 cm^3 or about 1650 in^3

The dynamic part of the load on the a-arm is probably way bigger than you think. The damping force from the shock might be bigger than the spring force for normal motion of the suspension. Then you have to add cornering forces.