Knowing the difference between tractor and sprayer tires

Sprayer tires have developed over time to become very specialized to minimize soil compaction and ensure precise handling at high speeds — it’s not quite a one-size-fits-all market. 

There are instances where tractor and sprayer tires can be used interchangeably, and others where they can even be the same size, but there are key differences in use and tread design. 

Sprayer tire needs

“Compared to a tractor tire, the stability of a sprayer tire is of utmost importance,” says David Graden, global account executive for agriculture at Michelin. “Sprayer tires are specifically designed to handle the constant pitch and sway of a machine loaded with liquid, in addition to the dynamic loads, with a very high center of gravity. As these machines continue to get larger and carry heavier loads, the tires also must meet or exceed these demands.”

Tractors in North America are commonly rated at Speed Rating B (30 mph), high-clearance sprayers often travel at Speed Rating D (40 mph), with some traveling even faster. These speed ratings will be marked on the sidewall of the tire, alongside the Load Index.

Higher speeds will cause more movement in the lugs of a tire, or tread squirm. More movement creates friction and heat — bad for rubber, and increases rolling resistance — making the lug design of a sprayer tire look very different compared to a tractor tire.

Sprayer tires usually have an R-1 tread design to provide more stability, less heat build-up, and a smoother ride on the road, according to Norberto Herbener, OE applications engineer at Trelleborg. Tractors often use an R-1W design, with lugs 20% taller than the R-1, to achieve higher pulling power, and traction transfer from the tractor to the ground.

Sprayer tires have a lower lug void — the space between each lug on the tire — creating more surface contact and enabling a smoother ride. Sprayer tires will often have more and wider lugs than tractor tires, to help guarantee stiffness when the sprayer is operating with a full tank load. 

“A high void ratio means there is more gap in the tread, than rubber contacting the driving surface,” says Dana Berger, ag business development manager at Continental Agriculture. “This is a benefit for self-cleaning efforts and soil compaction, common to tractor tires.”

In most cases, the shorter block and wider tread of an R-1 tire is better suited for a sprayer, according to Berger. While a sprayer has a loaded tank, it will experience the effects of inertia as it drives faster or slower, or stops. The sloshing in the tank can cause the sprayer to rock, and create uneven wear on an R-1W tire.

During the spring, and sometimes in the fall, when the soil is moist, soft, and normally no row crop is in place pre-emerge, a wider tire on the sprayer is better to float more on top of the soil.  Consequently, a larger cross-section or tire width is preferred, says Herbener.

VF tires

VF tires are capable of carrying 40% more load at standard air pressures, says Greg Gilland, vice president of global agriculture for Maxam Tire. This allows high-clearance self-propelled sprayers to carry the same load at reasonable air pressures, without compromising soil compaction. 

Gilland provided the following example: A standard 380/90R46 AGRIXTRA N tire rated at 159A8/B can travel at 25 to 30 mph with a maximum load of 9,645 pounds at 58 PSI. A VF380/90R46 AGRIXTRA N rated at 173D can travel at 40 mph with a maximum load of 14,330 pounds at 64 PSI. 

At nearly the same air pressure, the VF can carry 4,600 pounds more at 10 mph faster than the standard. For a standard tire to carry nearly the same weight, air pressure would need to go up, and the sprayer would need to slow down below 30 mph. 

“In sum, as a general rule the following sets a sprayer tire apart from a tractor tire: lower void ratio, higher weight carrying capacity, shallower tread, and higher speed rating,” says Gilland.

Editor's Note: This content originally appeared in AG Tire Talk to provide answers that farm equipment dealers have about farm tire technology. This series features a trending question followed by an abridged version of the answers. For the complete answers, check out agtiretalk.com.