Some off-road vehicles have the spare tire mounted externally on the rear door for several practical reasons:
Space efficiency: Off-road vehicles often need more interior space for passengers, gear, or cargo. Mounting the spare tire outside frees up room inside the vehicle.
Ground clearance: Mounting the spare tire underneath the vehicle, as is common with many regular cars, can reduce ground clearance. This isn't ideal for off-roading, where more clearance is crucial to navigate rough terrain.
Easy access: A rear-mounted spare tire is easier to access, especially in muddy, rocky, or uneven environments-situations common in off-roading. You don't have to crawl under the vehicle to retrieve it.
Larger tires: Off-road vehicles often use larger, heavier tires. The rear door provides a sturdy mounting point that can support the size and weight of these tires better than other locations.
Design tradition: Some models, like the Jeep Wrangler or Toyota Land Cruiser, have a long-standing tradition of rear-mounted spare tires, which also contributes to their rugged aesthetic and brand identity.
Overall, the rear-door mount is a practical and functional solution for off-road needs.
