Why Do Some Lawn Mowers Have Such Large Rear Wheels?

When it's time to purchase a new mower, you might focus on the top-rated self-propelled lawn mowers to keep your grass beautiful. Within those models, you might want to pay attention to key features like the deck cutting width or the pros and cons of gas- versus battery-powered lawn mowers. When looking more closely at the design of walk-behind models, you might also wonder why some lawn mowers have large rear wheels. It turns out there's an important purpose: This design helps with maneuverability when going over uneven terrain in a yard.

Sometimes, the difference in wheel sizes is extremely noticeable. With the Toro 21321 Recycler Self-Propelled Lawn Mower, the rear wheels have a 10-inch diameter, while the front ones measure 8 inches. The Cub Cadet SC300C Signature Cut Self-Propelled Mower uses even bigger rear wheels at 11 inches in diameter while offering an 8-inch wheel on the front.

Typically, you'll find that inexpensive machines have the same size wheels in front and back. For example, the Pulsar Push Lawn Mower has only 7-inch diameter wheels all around. The Pulsar mower is less than half the cost of the Toro and Cub Cadet models mentioned earlier, even though all three units have 21-inch cutting decks (The Pulsar unit is not a self-propelled design). Models with the same diameter on the front and back are called low-wheel designs, while models with larger diameters in the rear are called high-wheel models. These size distinctions matter when it comes to certain mowing tasks.

The primary advantage of larger rear wheels on a lawn mower is helping navigate uneven terrain. The larger back wheel is less likely to bottom-out in a rut, spanning the rut instead. This design reduces the chance of the mower deck bottoming out and scalping the grass by cutting it too short when the wheels bounce in a rut or other obstacles, and the deck makes contact with the ground.

Are bigger wheels better on a lawn mower you're using with hills? Self-propelled mowers are often the best type of lawn mower for a hilly yard, and part of the reason is the larger rear wheels they frequently have, where the larger diameter simplifies navigating inclines. They provide extra traction, making it easier and safer to move the machine up the slope. If the grass is a little wet, the extra grip and traction is especially helpful.

Although the larger rear-wheel designs make it easier to maneuver over bumpy terrain, some manufacturers partially negate the advantage found with high-wheel mowers with the design of the machine. If the manufacturer pushes the motor on the mower farther forward on the deck to compensate for the space needed for larger rear wheels, it can make the machine feel far heavier when tipping and turning it 180 degrees when you reach the end of a mowing path. If you go back and forth in your yard a lot, pay attention to the position of the motor.