This season has seen seven colours used in a 'rainbow' range of tyres stretching from super-hard through hard, medium, soft, super-soft, ultra-soft and hyper-soft.
Compounds will still vary in 2019 to suit individual track characteristics, with the soft used at twisty Monaco very different from the same colour code at high-speed Silverstone or Suzuka.
Pirelli told reporters at the U.S. Grand Prix that the number of compounds available to teams would become known in December after the governing FIA had given formal approval.
The sport's sole tyre maker said the new system would make it easier for the casual fan to know what was being used while more detail would still be available to those who wanted it.
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"We've been talking about this with the teams, FIA and Formula One for a while," said Pirelli's racing head Mario Isola.
"The idea behind the change is to make all the tyres more easily recognizable and explainable -- specially for television -- while still clearly denoting which specific compounds are being used at each race."
Isola had said in January, in the face of concern that the rash of names and colours would be confusing for fans, that Pirelli felt using just three tyre designations would be 'dumbing down' the sport.
Harder tyres are slower over a lap but longer lasting while softer ones are quicker but lose performance sooner.
Three tyre types from within the range are currently selected for each race.
(Reporting by Alan Baldwin, editing by Martyn Herman)
