Question

Why Lorries And Trucks Carrying Heavy Loads have 8 tyres instead of Four ??

Answer 1

Lorries and trucks carrying heavy loads have 8 tyres instead of four. Also the tyres are broader because this increases the area of contact with the ground, thus reducing the pressure exerted on the ground.

Pressure is given as: $Pressure=\frac{Force}{Area}$

Heavy trucks apply more force on ground which increases the pressure as well and this can damage the road. We can't decrease force to decrease pressure so we increase the surface area so that pressure exerted on ground can be reduced as they are inversely proportional.