If you need tyres for the 18-inch wheels on your W177 Mercedes-AMG A 35 4MATIC, check out Tyres.co.uk. There you will find Michelin Pilot Sport 5 and Continental PremiumContact 7 in size 225/45 R18 95Y XL. This is the only confirmed factory fitment (not all A-Class size), so check registration, placard, load index, and run-flat specifications before buying.
For the Mercedes A Class, more info on tyres can be found on the tyre-pressure info sticker that is located on the inner side of the fuel filler flap. The tyre pressure ratings and info on the vehicle is on the sticker and the complete fitted tyre size and rating are on the sidewall. The book is also helpful if there are factory wheel options.
It is worth noting most Mercedes A Class models do not require four new tyres. When new tyres are fitted, ensure they are at least a pair, same size, same type, same load and speed rating, fitted on same axle. Keep in mind for the 4MATIC version of Mercedes, when replacing two tyres, ensure that the tyres and rolling circumferences are matched on all four wheels.