Firestone tyres will continue to be a part of the IZOD IndyCar Series through to the end of at least the 2018 season, it was announced on Friday.

"The Firestone brand's significant contributions to IZOD IndyCar Series racing are the result of more than 100 years of experience competing in this sport, most recently as part of a continuous 22-year partnership," said Jeff Belskus, the interim president and CEO of IndyCar. "This is an important relationship for both Firestone and IndyCar and we are very pleased to continue the association."

"Firestone performance and safety have been synonymous with Indy car racing for more than 100 years," said Al Speyer, the executive director of Firestone Racing. "We are excited about the opportunity to continue the ongoing success of this series by extending the Firestone brand's history in the sport through the 2018 season.

"We treasure the relationships we have fostered with the league, drivers, owners and various other partners involved with the sport through the years, and look forward to continuing our legacy of high performance for which Firestone tires are known," he added.

Firestone - which has supplied tires to the IZOD IndyCar Series since the league began in 1996 - caused shockwaves within the sport in March 2011 when they announced they were pulling out of US open-wheel racing at the end of last year. However, a week later IndyCar was able to negotiate a reprieve that persuaded Firestone to remain as the series' tyre supplier for two more years through to 2013.

However, that still left doubt about what would happen beyond the end of next season. Rumours that former IndyCar CEO Randy Bernard was preparing for a split with Firestone by undertaking negotiations with rival tyre suppliers was said to be one of the factors that led to his exit from his role, as most team owners preferred focussing on keeping Firestone in place.

The expanded agreement announced on Friday begins in 2014, and includes not only tyres and technical support but also investments in advertising, event promotions, at-track signage, hospitality, race title sponsorships and other programs. Firestone will continue with their title sponsorship and official tyre status of the Firestone Indy Lights series through 2013.

As well as continuing their title sponsorship of the Firestone 550 at Texas Motor Speedway in June, Firestone will also now be the official tyre of the race season kickoff in St. Petersburg and the third race of the year at Long Beach, Calif. The company will also continue their tradition as the Official Tyre of the Indianapolis 500 Mile Race - including the 100th running of the race in 2016.

"The agreement expands our opportunity to continue working together to provide on-track excitement for our fans and grow the sport through coordinated and consistent off-track promotions," said Belskus.

"Our partnership with the IZOD IndyCar Series is based on mutual respect and benefit to all parties," said Firestone's Al Speyer. "Our agreement to move forward together is a manifestation of the business value we both realize from this partnership as well as the legacy of safety and performance that we have built together over a century of experience.

"We are proud to continue our tradition of exceptional support for the IndyCar Series," he continued. "One of our future aims is to help grow interest, so we look forward to welcoming a new generation of fans to the sport while at the same time energising the existing loyal fan base. Fans are the true end customer for both IndyCar and Firestone, and their engagement is fundamental to our mutual future success."

Specific details of the agreement and relationship will be announced next year.