Get a set of stickers
2 x names & 2 x numbers so you can decide if you want names or numbers on each side or even both... plus have a spare to stick on your wifey's car.
The max print area for most helmets is 16cm x 10cm high. Your name and number will be fit into those dimensions but kept in proportion (e.g. if you chose a skinny font and only have 1 number then your helmet sticker might end up being 10cm high but only 10cm wide. Please email if you have specific requirements.