For the Vauxhall Tigra TwinTop 2004-2009, tyre options at Tyres.co.uk include Michelin Primacy 4 and Goodyear EfficientGrip Performance, which are available for 185/55 R15-sized tyres, with the former being an 82V and the latter an 82H. Check the registration and the placard on the passenger door, as some other factory wheel options have different fitments.
The Vauxhall Tigra tyre size is moulded into each tyre sidewall. To see the tyre pressure specifications, open the front passenger door and look on the door panel. The information there, combined with the handbook, will help confirm the factory fitment. It's important because different wheel and tyre options were supplied with the Tigra.
Every factory version of the Vauxhall Tigra has front-wheel drive, so no drivetrains require all four tyres to be the same. Replace tyres as an axle pair where possible and with the same size, make, model, and tread design on that axle. When changing two tyres, the new pair should be fitted to the rear axle.