The 1955 Mercedes Benz Model 300 SLR sure is a swanky car, but just where were you planning to put the groceries?

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How many soccer kids can you fit in your backseat? How many pieces of luggage can you cram into your trunk? If you're like most drivers, you've faced down equal or greater challenges trying to pack everything in. At one point or another, you'll need all the free space you can manage, which doesn't leave a lot of room for an extra tire.

Let's face it: Even small, donut spare tires are dirty and cumbersome, and they take up space like nobody's business. Full-sized spares, while more useful, require even more room. Plus, if you're towing a trailer behind your vehicle, the last thing you want is a flat tire on your hands and no spare.

F­ortuna­tely, many vehicles and trailers feature external tire mounts, where locking bars or bolts hold the tire in place. But what do you do if you need one or more spares and simply lack room in the trailer or sufficient, existing tire mounts?

Luckily, there's hope. In many cases, you can simply install a spare tire mount on your vehicle or trailer. In this article, we'll examine the different kinds of spare tire mounts, how to choose the best one and how to install it.