Pirelli's planned mid-season Formula 1 tyre tweaks are set to be much smaller than originally anticipated after the FIA ruled that changes will only be allowed on safety grounds.
Sources have revealed that the governing body has told Pirelli that it is happy to accept - and is indeed keen for - alterations necessary to prevent a repeat of the rear tyre delaminations that have struck at the last few events.
But, in a blow to outfits like Red Bull hoping further tweaks would help them overcome tyre difficulties they have faced, the FIA has made it clear it will not tolerate further changes aimed at reducing the number of pitstops or decreasing degradation.
Sorting out the issue must also not lead to a change of specification back to the 2012 tyres, as some had suggested could happen.
Instead, Pirelli has been instructed to solve the matter by modifying the current specification of tyres. It is now close to finalising tweaks in this direction.
The FIA is basing its stance on Article 12.6.3 of the technical regulations, which has also been cited by teams to Pirelli amid questions about the legality of a bid to change the specification.
The rule states: "Tyre specifications will be determined by the FIA no later than 1 September of the previous season. Once determined in this way, the specification of the tyres will not be changed during the championship season without the agreement of all competing teams."
Although another clause in the regulations says that changes can be introduced if the tyres are deemed by the tyre supplier and technical delegate as 'technically unsuitable', the FIA does not believe that the current high degrading nature of the tyres that sometimes requires four stop races falls under that banner.
An FIA source told AUTOSPORT: "Discussions between the FIA and Pirelli are ongoing regarding the tyre failures and making changes to prevent them happening again. These talks do not involve the subject of degradation or the number of pitstops."
CHANGES NOW SET TO BE MINOR
Pirelli has not yet settled on what changes it is making to the tyres, but its motorsport director Paul Hembery suggested on Friday that revisions were likely to be small.
"Let's wait and see exactly what changes we will be making, but we are doing everything we can to minimise what will be different," he told AUTOSPORT.
The stance from the FIA, allied to Hembery's suggestion, looks likely to be good news for outfits like Lotus, Ferrari and Force India that had been concerned a wholesale change of tyres could hurt the advantage they currently have.
Lotus boss Eric Boullier aired his frustration earlier this week at Pirelli planning mid-season changes, but expressed his hope that any tweaks would be minor.
"That there are changes to come can be seen as somewhat frustrating, and I hope they are not too extreme," he said. "It's clear that Pirelli have found themselves in a difficult situation and under pressure from different quarters."