The world's fifth largest tyre maker was delisted from the Milan stock market in 2015, where its shares had traded since 1922, following a mandatory offer launched by an investment vehicle controlled by China National Chemical Corp (ChemChina).

Pirelli is expected to make a file its listing request with market regulator Consob these days, one of the sources said.

"The idea is to conclude the IPO either in late September or early October, it's a pretty tight schedule," the source said, adding that the final timing will depend on Pirelli securing all the necessary regulatory approvals.

Pirelli is eyeing a listing start on Oct. 4, the person added, confirming a date cited in Italian media.

Pirelli declined to comment. The company has previously said it planned to list in the fourth quarter of this year.

The tyre maker said in April ChemChina was willing to reduce its stake to below 50 percent "for the greater success of the IPO".

State-owned ChemChina holds a 65 percent stake in Marco Polo International Italy, the sole shareholder in Pirelli. Camfin, an Italian holding company whose investors include Pirelli boss Marco Tronchetti Provera, Italian banks UniCredit (>> UniCredit SpA) and Intesa Sanpaolo (>> Intesa Sanpaolo), has 22.4 percent and an investment fund linked to Russia's Rosneft (>> NK Rosneft' PAO) owns the rest.

As part of the ChemChina deal, Pirelli's less profitable truck and industrial tyre business was folded into the Chinese group's listed unit Aeolus (>> Aeolus Tyre Co., Ltd), leaving the Italian company to focus on the operations that supply tyres for cars, light trucks and motorbikes.

In that business, Pirelli has been focussing in recent years on more upmarket tyres for brands such as Mercedes, Audi, and BMW -- luxury carmakers which have weathered the latest downturn in the industry better than their mainstream rivals.

For the first quarter of this year, which marked the launch of Milan-based Pirelli as a pure consumer tyre player, the company reported revenues of 1.34 billion euros and earnings before interest, taxes, depreciation and amortisation (EBITDA) of 270.3 million euros.

The premium business accounted for 67.8 percent of overall sales.

(Reporting by Elisa Anzolin, writing by Agnieszka Flak, editing by David Evans)

By Elisa Anzolin