As we all know, the front wheels are not the main load-bearing wheels, but rather serve a steering function. During steering, the outer edge of the tire is prone to scraping against stones or road edges on either side, requiring the convex surface of the rim to face outwards.
Even if it snags on a hard object, the convex surface of the rim bears the weight, preventing tire punctures and loss of vehicle control, thus avoiding danger.
The rear wheels bear the remaining weight of the vehicle, requiring a larger load capacity. This is why many trucks have a double-row rear wheel design. On one hand, the double-row design increases the contact area between the wheel and the ground, thus increasing friction; on the other hand, it also increases the vehicle’s load-bearing capacity.
If the convex surface of the rim faced outwards, the two tires would require exceptionally long bolts for installation, making installation inconvenient and reducing vehicle safety.
From a mechanical design perspective, the concave surface of the rim is more resistant to pressure. Furthermore, the two rear wheels being joined together ensures a stable connection, saves space for brake pad installation, and, more importantly, increases the load-bearing area and strength.
Now you know why truck rims are convex at the front and concave at the back. What other little-known facts do you know about trucks? Feel free to leave a comment below.
