Tractor Tyres: Radial vs Bias Ply Tyres
Everyone in the tyre industry say they know the difference between Radial Ply and Bias Ply tyres, but what is it really?
The Harvest radial ply tyres have single or multiple nylon plies running radially, bead to bead, with the tread being reinforced with an inextensible reinforcing polyester belt package.
The Harvest bias ply tyre has multiple nylon diagonal plies (30-40 degree angle), bead to bead, and diagonal breaker plies can be used to reinforce the tread. The two constructions make the pneumatic tyre look and operate differently in both field and road applications.
Differences In Service Operation
For all pneumatic tyres “AIR CARRIES THE LOAD”. This rule does not change for Radial or Bias Ply tyres. The air pressure inside the tyre is equal to the contact pressure on the ground in both cases with the exception to Harvest x-load tadial tyres that can create a lower pressure.
The Harvest radial ply tyre has a longer and narrower contact patch with the ground when compared to the Harvest bias ply tyre. The Harvest radial polyester belt holds the tread pattern and keeps it stable as the tyre rolls through the contact patch at various speeds. The tread pattern always compresses together as it goes through the contact patch and the radial polyester belt supports the tread pattern so that it compresses evenly. This allows for low soil compaction whilst maintaining traction.
A radial ply tyre is like a caterpillar track on any rubber or steel track vehicles. It sits the tread pattern on top of the surface. The circumference of the belt is the rolling circumference of the radial tractor tyre.
The bias ply tyre is not as rigid as the radial ply tyre under the tread pattern. The tread pattern moves and squirms as the bias ply tyre rolls through the contact patch. The bias plies also move over each other as the tyre distorts in the contact patch. This increases the tread squirm. The bias ply tyre conforms to the shape of the ground surface. It envelopes around small rocks and ruts rather than bridging over them as in a radial ply tyre. This additional squirm and movement are why the bias ply tyre tread pattern wears more quickly than the radial ply tyre. It is also the reason for its shorter and wider contact patch and means that it is prone to overheating.