Tilley originally participated in cycling before a knee injury forced him to quit the sport, and he began kart racing at the age of eight. He later raced in Formula Ford, a series with high financial demands that forced him to work three jobs—a delivery driver for a catering business, a mechanic for a Historic Formula One Championship team, and a sales assistant—to pay for crew members and the car. In 2010, he won the Castle Combe Formula Ford 1600 Pre 90 championship.
He moved to sports cars in 2011 and spent the next two years driving for Topcats Racing in Britcar. Plans to return to full-time open-wheel racing in 2013, competing in the British Formula 3 International Series for his own team, were aborted; in May, he made a guest appearance in Formula Ford 1600 at Castle Combe Circuit where he finished tenth.
Tilley continued sports car racing upon moving to the United States. In 2015, he and co-driver Jerry Kaufman won a 13-hour endurance race at Virginia International Raceway sanctioned by the Sports Car Club of America.The following year, the two joined Continental Tire SportsCar Challenge team BimmerWorld to race in the ST class.Tilley and Kaufman continued to drive together in the 2017 Pirelli World Challenge SprintX GTS class for The Racer’s Group, where they finished second in the championship.
In 2019, Tilley started racing in Historic Formula One. Driving a 1977 Ensign N177, he won at Circuit Zandvoort and Circuit de Spa-Francorchamps, both races in wet conditions, and finished third in the Fittipaldi Class standings. Tilley’s vintage racing also saw him create his team Era Motorsport, which began racing in the IMSA SportsCar Championship LMP2 class in 2020. The project was spurred after Tilley befriended tech company businessman Dwight Merriman, with whom he started worked as a touring car racing driver coach in 2018.
Era Motorsport’s debut came at the 2020 24 Hours of Daytona, in which the team ran an Oreca 07 for Tilley, Merriman, Ryan Lewis, and Nicolas Minassian. The team initially formed a partnership with DragonSpeed before opting to run the full LMP2 season as a standalone operation. The car finished third in the LMP2 class, followed by Tilley and Merriman scoring three more podium finishes that year. The duo also entered the 24 Hours of Le Mans for IDEC Sport alongside Jonathan Kennard; despite Merriman crashing in practice and being replaced by Patrick Pilet for the race, the car finished 15th. Although Era was second in the LMP2 standings with three races remaining, the COVID-19 pandemic and Merriman’s injuries prompted the team to withdraw from the championship.
In 2021, Era allied with Jota Sport to field an LMP2 for Tilley and Merriman in the Asian Le Mans Series. Tilley, Merriman, and Andreas Laskaratos claimed the LMP2 Am division championship after winning all four races. Era also won the 24 Hours of Daytona LMP2 class with Tilley, Merriman, Ryan Dalziel, and Paul-Loup Chatin. In April, Tilley and his team started competing in the European Le Mans Series.
Tilley began dabbling in stock car racing in May 2021 when he joined Live Fast Motorsports for the NASCAR Cup Series‘ Texas Grand Prix at Circuit of the Americas. His schedule in the team’s No. 78 also included races at Road America, Watkins Glen International, and Indianapolis Motor Speedway.