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Tyre Tips - Agricultural

Right Tyre Pressures = Longer Farm Tyre Life!!>>

Never overload your tyres. There is an old saying that tyres can’t heal themselves. Once you do
damage to a tyre, that damage remains throughout the life of the tyre.


Inflation pressure is determined by the load carried by the tyre, and in all cases the tyre must
be matched to the load.


Overload and under inflation have the same affect on the tyre. This will affect both the bead area
and shoulder of the tyre, causing radial cracking in the shoulder and chaffing on the bead and bead




20.8/520/85R-42 Firestone Radial AT 23 load index 157A8/B
157 = 4125kg A8 = 40 kmh B = 50 kmh


This tyre will carry:

Single Duals
4,125 kg @ 23psi 3,363 kg @ 23 psi
3,350 kg @ 17psi 2,795 kg @ 17 psi
2,575 kg @ 12 psi 2,272 kg @ 12 psi
1,850 kg @ 6 psi 1,495 kg @ 6 psi


When using triples the pressure changes again.


Always remember the air carries the load not the tyre. The air pressure also will determine the correct
foot print on the ground.


There is no short cut. You should always use the correct rim and tube for the tyre. In regard to rim fitment, please contact your closest dealer.


It is not recommended to use water in tyres for ballast. However if you do use water, it is
not recommended filling more than a quarter of the tyre.


Eg - always put the valve at 4 o’clock.


It is always advisable to use dry weight bolt on or suitcase weights.



This should be done by a professional or a person trained in fitting tyres, as it is a very dangerous practise for the untrained.

Tyres should always be stored under cover in a dark place and away from any electrical equipment. The sun will cause ozone cracking and perish the inner liner.