How can I find the correct tyre size that fits my tractor / agricultural vehicle?

Finding out which tyre sizes fits your tractor can be a difficult task. On this page we will explain where you can find the tyre size on you tyre and how you can understand this number.

The tyre size of a tractor or agricultural vehicle is printed on the side of the tyre. This is better known as the sidewall of the tyre. The image on the left shows an example of a letter/number combination that can be find on a tractor.

The number IF710/70R38 is shown on the image. We will use this number to elaborate the system on how to interpretend the tyre codes for tractors.

A tractor tyre consists of different aspects. We will use tyre code IF710/70R38 to explain on how the tyre works.

The first to 2 letters in this example IF shows that this is a tractor tyre with special tyre technology. If a tyre has the identification VF or IF at the beginning of the sidewall, this indicates that the tyre is equiped with soil protection or soil friendly tyres.

These 2 types of tyres can be driving with 20% lower tyre pressure but also cary more than 20% extra load. If tyres are deinflated with 20% the tyres have more contact area than standard tyres. With more contact area, the load will be better spread and this will avoid excessive stress on the soil.

If a tyre is not equipped with this type of technology the first 3 digits will show the tyre width of the tyre

Tyre height is indicated after the slash ( / ) in the tyre size. The height of the tyre is given in percent, a height of 70 means that the tyre is 70% of the width of the tyre.
In this case the height is 70 % of 710 mm.

The letter R indicates that this is a radial tyre.

After the letter R (that indicates radial tyre) there is a number. In this instance it is number 38. This number indicates the size of the rim in inches. 

After the rim size there is a number and one letter left. The last number indicates the Load index of a tyre. The load index indicates on how much you load you can carry. This is very important with tractor tyres.

The common load index numbers of work van tyres have been collected in one overview. You can find this overview a couple of paragraphs down

After the load index number, there is still one letter left. This letter shows the speed index of the tractor tyre.

The common speed index numbers of work van tyres have been collected in one overview. You can find this overview a couple of paragraphs down

Work vans and light commercial vehicles have specific load capacity rules. It is therefore very important to choose the right tyre that corresponds to the load capacity indicated by the manufacturer of the truck or trailer.

Periodic inspections check whether the tyres correspond to the load capacity specified by the manufacturer. If this number is not correct, the entire truck or trailer will be rejected.

In the overview on the right you can see the speed rating that can be found on the side of the tyre with the corrosponding maximum speed rating.