Why do some tractors have large wheels?

[GoJDpuller]

I went by a McCormick dealer today and saw a front wheel assist tractor with really large wheels, the tire side wall was only about a foot. Whats the reason for this?

 

[IaGary]

The bigger the diameter, the larger the footprint on the ground for more traction.

If you go to a wider lower tire to get a bigger foot print the wheels won't fit as well between the narrow crop rows.

Gary

 

[oj]

the larger the diameter of the wheel the lower the rolling resistance, this is why old wagons and the like used behind horses had large wheels: they're easier to pull.

 

[Bill(Wis)]

For the reasons below and the fact that "organic" farming is catching on and will require row crop cultivation. "The more things change, the more they stay the same."

 

[Hugh MacKay]

Aside from the reasons given below, large diameter tires with no more rubber on the ground than small diameter wide tires, give better traction and more flotation. My dad saw this 60 years ago, traded a W4 with 14x26 tires off for an H with 11x38, very close to the same square inches of rubber making contact with the ground, both tractors having basically the same power train, yet the H was all over the W4 on drawbar pulling on soft soil. Basically a field situation across much of eastern North America, with annual rainfalls exceeding 36". You go to hard roads or the mid west to prarrie firm soils and rainfalls much less than 36" and the wide small diameter tire will do just as well. By the way those mid west to prarrie soils are firm because they don't have the rain fall.

Large diameter tires also do much better in sandy to sandy loam soils. That and the reasons others gave is precisely the reason why any given tractor has wheel and tire options. Depends on who buys it, and what they are going to use it for.

 

[Ken Macfarlane]

The reason for a short side wall is to prevent or reduce power hop when under heavy drawbar load or poorly ballasted situations.