F1 to feature 18-inch wheels from 2021 onwards

HOCKENHEIM, Germany -- Formula One will switch to bigger wheels and low-profile tyres for the next regulation cycle starting in 2021.

The FIA has issued a tender to be F1's single tyre supplier from 2020, and in doing so published the proposed changes to the tyre regulations for the following season. The regulations confirm a move to low-profile tyres on 18-inch rims and a ban on tyre blankets from 2021 to 2023. The front tyres will be narrower, reducing from 305mm in width to 270mm while the rear tyres will remain 405mm wide.

Pirelli tested 18-inch rims in 2014 when the idea of low-profile tyres was first mooted, but it was mainly to offer imagery of the different tyre size.

A ban on tyre blankets has also been discussed before and will create a significant technical challenge for the tyre manufacturer. Banning tyre blankets has long been discussed as a cost saving measure and will make it more difficult for drivers to warm tyres, something which is crucial to unlocking their full performance potential. The rules state that the new tyres must "provide safe performance when leaving the pits cold".

There will also be a low temperature tyre provided for winter testing when F1 traditionally travels to Barcelona to test new cars in late February and early March.

In line with major changes to the technical regulations to aid overtaking, the 2021 tyre rules mention the "improvement of the show" as a top priority. F1 wants the next set of tyres to allow drivers to push to the maximum for longer during races while also creating enough strategic variation to spice up race weekends.

Tyre degradation -- which determines how long a tyre will be used and defines its window of peak performance -- is "considered desirable both for its impact on race strategies and to ensure tyres are not run to a point of excessive wear". The tender outlines the expected levels of degradation and differences in performance between the three compounds on offer each weekend.

The medium compound tyre will need to be 1.0s faster than the hard and the soft 1.2s faster than the medium. Meanwhile, the performance of the soft should degrade by two seconds by 10 percent of the race, the medium should degrade by two seconds at 18 percent race distance and the hard should degrade by two seconds at 22 percent race distance. The FIA hopes that will allow for a mix of one-stop, two-stop and three-stop strategies at races, with a ones-top impossible if drivers are using the softest compound tyre.

The regulations also state: "It is expected that aggressive driving or close following will incur higher tyre degradation per lap than gentle driving or driving in free air. Once a period of aggressive driving or close following ceases, the tyre should rapidly recover the lower level of degradation per lap associated with the more benign conditions."

In terms of absolute performance, the FIA has requested that new tyres are at last as good as the current tyres.

Submissions from interested parties are required by the end of August. Pirelli took over from Bridgestone as F1's sole supplier in 2011 and has previously expressed a desire to continue in its current role.

The nature of the newly-issued tender means any new manufacturer wishing to supply the sport will be required to create one set of tyres to conform to the 2020 regulations before designing an entirely new set for the following cycle of rules.