Even as, amid threats to quit the top flight, Pirelli attempts to seal an extension to its current F1 contract, a potential replacement - or rival - is putting its prototypes through their paces.

According to tyrepress.com, which claims official word from the manufacturer itself, Kumho has tested with its own F1-spec rubber, although the tyres are not destined for the likes of Ferrari, Red Bull and McLaren just yet.

Although Kumho first stated an interest in F1 as long ago as 2004, and has been touted as a potential replacement for whichever rival was currently in occupation ever since, the new tyres are actually earmarked for Auto GP, which exists among the plethora of feeder series on the single-seater ladder.

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According to a quote attributed to Kumho, the three-day test at Barcelona's Circuit de Catalunya was designed to 'validate the technology for future business with F1 and to actually test the technology accumulated through motor sports since the 1990s for F1."

Kumho is no stranger to the junior formulae, having been sole supplier to the F3 Euroseries in the past, and sees motorsport at all levels as a means of both developing its product and enhancing its image.

"As we are a relative newcomer, with the shortest history among the global top ten tyre makers, we need to compete in the global market with our technical power, and motor sports is the area where we can show off our capabilities," chief executive Jong-Ho Kim told Tyres and Accessories magazine back in 2010, "We already completed the development of F1 tyres in 2007 and now watch for an opportunity to enter into the F1 market as well."

Pirelli has revealed that, despite not yet having inked a new contract, it will take its 2014 tyres to the season-ending Brazilian Grand Prix to give teams the chance to sample the new rubber ahead of next season.

Drivers will be given the chance to run on the prototype tyre during the opening practice sessions at Interlagos, with Pirelli then hoping to run a number of other tests over the course of the winter. The Italian company will also run a test with McLaren at Vallelunga, using an older-spec car, to continue work on the new tyres which would otherwise have been conducted at an aborted session in Austin.

"[The contract] is done really," motorsport director Paul Hembery said prior to the Abu Dhabi GP, "There's one last piece to be done with the FIA. The lawyers are dealing with that - when you get lawyers involved with anything it tends to add time to whatever you're doing. So, it's just rumbling along."