Why are tractor tyres so big? The science behind their size
21st March 2025
One of the most distinctive features of tractors are their huge tyres. Compared to standard road vehicles, tractor tyres are wider, taller, and built for durability.
In this article, we’ll break down the science behind tractor tyre size and how it benefits farmers in the field.
Spreading the load
Soil compaction is a major concern for farmers. When heavy machinery presses down on the ground, soil is compressed, reducing aeration and drainage making it harder for crops to grow.
Large tyres help prevent this by spreading the weight over a larger surface area. This reduces the pressure per square inch on the soil, minimising compaction and preserving soil health.
Tractor traction
Farmers are often working on muddy, uneven, or soft terrain. Large tyres increase the contact area with the ground, improving grip and reducing the chance of tractors getting stuck.
This is especially important for:
- Ploughing – where deep soil contact is needed
- Towing heavy loads – ensuring the tractor can pull trailers, balers, or sprayers without slipping
- Working on slopes – providing stability on uneven ground.
The deep treads on tractor tyres are also cleverly designed to self-clean, preventing mud from clogging the tyre and reducing traction.
Increased stability
Tractors generally have a high centre of gravity, potentially even more so when carrying heavy equipment.
Large wide tyres that are spaced far apart help provide a wider base, improving stability and reducing the risk of tipping – especially on hilly, or uneven terrain. This plays a crucial role in farm safety, as tractor rollovers are a leading cause of farm accidents.
Reduced fuel consumption
Bigger tractor tyres reduce the amount of rolling resistance, meaning tractors require less power to move across fields. This improves fuel efficiency and reduces operating costs over time.
A narrower tyre would sink deeper into soft ground, increasing resistance and forcing the engine to work harder. Wider tyres are able to “float” on the surface, requiring less effort to move.
Radial vs bias-ply
There are two main types of tractor tyre:
- Radial tyres – more flexible, offering better fuel efficiency and lower soil compaction
- Bias-ply tyres – more rigid, offering stronger sidewall support for heavy loads.
Radial tyres are now preferred for most farm applications because they allow for larger surface contact without excessive weight, improving performance. However, bias-ply tyres still find utility as a cheaper alternative.
To conclude, tractor tyres are big for good reason – they protect the soil, improve traction, enhance stability, reduce fuel costs, and handle heavy machinery effectively.
While they may look oversized compared to regular vehicle tyres, their design is essential for modern agriculture.
Ascenso helps farmers choose best tyres.
