Why Do Some Motorcycles Have Fat Tires?

There are few things as distinctively cool as a big, rip-roaring motorcycle, tires cutting a mighty swath through the sunswept highway. Those tires, in particular, go a long way toward creating a beefy motorcycle's muscular vibe. Motorcycle tires are on much more prominent display than car tires, after all, especially if there's a motorcycle driving right behind you. If you've been watching a lot of beefy bikes, though, you may have started to notice that not all of them have precisely the same kinds of tires.

Some motorcycles employ wider tires than you may expect, or "fat tires" as they're known to some. Larger tires do certainly have their own vibe, one that goes well with a large motorcycle's already muscular profile. However, style isn't the only reason a rider may employ wider tires. Using larger tires can make several changes to a motorcycle's operation and general longevity. Different bikes for different riding styles need different tires, and certain kinds of bikes need beefier tires to do their jobs properly.

When you're driving on any kind of motor vehicle, motorcycles included, your tires make regular contact with the ground, ferrying you forward. The precise spot where the treads of your tire touch the ground is known as the contact patch. This is usually a fairly small spot, moreso on a motorcycle tire, but that small spot plays a large role in how much your tires grip onto the pavement (or whatever surface you're driving on).

Naturally, if you're riding on a motorcycle with larger, wider tires, the size of that contact patch is going to grow in proportion. With a larger contact patch comes a more powerful grip onto the road. It's kind of like the difference between lifting something with just one of your fingers versus all five of your fingers. A larger point of contact allows the tires to hold fast to the road, which in turn helps keep you stable on rough or uneven terrain. This is a big part of what gives muscular motorcycles like the Harley-Davidson Fat Boy or Fat Bob their strong constitutions. Heavier bikes need heavier tires to keep them properly rolling, and if you tried to stick smaller tires on there, the mass and pressure would wear them out very quickly. Poor tire selection is one of the worst things you can do for a vehicle's longevity.

While fat tires on a motorcycle do give the rider a lot more grip and look pretty cool, it's important to remember that they aren't a universal improvement over smaller tires. This is true for both motorcycles and cars.

Because fat tires are so much wider, they need to be leaned further than usual in order to take tight corners. There's some geometry to it, but the short version is that the wider the tire, the more you need to move it to one side to actually begin turning the bike. This means that, as a rider, you need to both put more force into turning your handlebars and physically lean further to the side to make a deep turn. Larger tires also mean heavier weight, and heavier weight means a bigger load for your motorcycle to expend fuel and power on lugging.