By Michelin Sport
June 19 2005

Formula One's two-race sojourn in North America concludes this weekend at the Indianapolis Motor Speedway, where Michelin will be aiming to extend its comfortable lead in the world championships for drivers and constructors. The United States has a long but fragmented relationship with grand prix racing. America's most prestigious domestic race – the Indianapolis 500 – counted towards the world championship between 1950 and 1961, to ensure that the nation had a presence on the calendar at a time when there was no suitable circuit for F1.

The first conventional United States GP took place at Sebring in 1959 – and there have since been another 47. America has hosted F1 world championship races at nine circuits, more than any other nation: Sebring, Riverside, Watkins Glen, Long Beach, Las Vegas, Detroit, Dallas and Phoenix preceded the purpose-built Indianapolis road course, which opened in 2000 to stage the first United States GP since 1991.

Michelin has yet to notch up its first victory at Indianapolis but has a proud F1 track record in America. Carlos Reutemann, Gilles Villeneuve, Alan Jones, Niki Lauda, John Watson and Nelson Piquet have all scored world championship grand prix victories for Bibendum on this side of the Atlantic.

In last season's United States GP, Takuma Sato was the highest- placed Michelin finisher.

"Indianapolis represents a real challenge," says Pierre Dupasquier, Michelin motorsport director, "because tyres have to cope with sustained heat build-up for more than 20 seconds as cars negotiate the season's longest flat-out section, which incorporates the banking and the pit straight. In addition, they also need to generate sufficient grip to maximise traction on the tight infield.

"These two contrasting characteristics oblige teams and suppliers to make compromises in terms of aerodynamic set-up and tyre compounds. The banking imposes a significant strain on the left-hand side of a chassis because it partly compensates for centrifugal forces by increasing vertical loads, which are then transmitted to the tyres.

"In fact, the banking limits the extent of what we can do when it comes to finalising our tyre compounds. We have to base our selections on this, the most demanding part of the track. Softer compounds wouldn't survive the banking but tyres that are too hard would struggle on the infield and would soon be chewed up through sliding around excessively. The surface of the banking is very abrasive – and that adds another contrasting factor to our preparations, because the infield is quite the opposite."