Suffolk PC Mark Bryant has reminded farmers to check which machinery items their 16-year-old workers can legally drive on the road.

Holders of the category-F qualification (for agricultural tractors) are permitted to drive tractors on the public highway but there are tight limits on the size of the machinery included on the licence depending on age.

This puts big trailers, combines and self-propelled foragers out of limits for some young drivers.

See also: 7 ways to drive your farm vehicle safely and legally

We talked to PC Bryant to explain the rules. He is from a farming family himself and has a lot of sympathy for youngsters doing their bit to help bring in the annual forage and combinable crops.

Here are some typical questions PC Bryant regularly gets asked:

My son has passed the tractor test for 16 year-olds and the tractor and trailer he uses is new. So how can that be breaking the law?

• It’s all about sizes of tractors and trailers.
• Sixteen-year-olds are not allowed to use trailers that exceed a total width of 2.45m.
• It dates back to legislation that was in place in the early 1980s and it is way out of date when it comes to using modern equipment.

How can my 16-year-old be legal on the roads then?

To be fully legal on the road, your 16-year old can only drive the following:

• A tractor with a width of less than 2.45m. Most tractors of more than 150hp and/or built in the past 20 years are likely to be wider than that.
• A trailer that has a maximum width of 2.45m (See above). That includes the extra width taken up by those fancy tailgate rams.
• A trailer that has close-coupled tandem axles where the centres of the axles are less than 0.845m apart. Most are considerably greater than that and 1.4m on a 16t grain trailer is not unusual.

“The rule of thumb is that if the tractor is big and shiny your 16-year-old won’t be legal to drive it. If it is small and old then you are probably OK,” says PC Bryant.

So how can my 16-year-old drive these vehicles?

• You’ll have to wait until they reach 17 and pass their car test.
• The good news is that once they hit 17-years-old they can drive a tractor with the full-fat 31t weight of tractor plus trailer and its contents under a category-B licence (a standard car licence).

What about tracked tractors?

• Youngsters cannot drive on the public highway in a tracked tractor such as a Challenger or Deere, says PC Bryant.
• That’s still the case even if you’ve taken your tracked tractor test – you cannot drive a tracked vehicle until you are 21.
• Also, you need to be 21 to drive a combine, self-propelled forager or self-propelled sprayer on the road.
• Check that your insurance gives specific cover for young drivers (including those between 13 and 16 who can’t legally go on the road anyway).