Always run 1/4 plates on mine, no problems with any of them.
Go Here:
http://www.platesforcars.co.uk/
You can decide whatever size you want.
I have ordered 203x152 for front & 330x89 for the rear.
Its illegal to fit plates with anything other than the standard sized lettering and spacing if there is provision for normal sized number plates to be fitted to the car. The only exception is for imported cars where there is no room to fit a standard sized plate then you can fit one with smaller 64mm letters.
You may get away with smaller plates/letters 99% of the time but sooner or later a cop who is bored and has nothing better to do will stop you and you'll be £30 (maybe more now) poorer
What is classed as 1/4 plates??
I was stopped with a smaller show plate on the front, he said his ANPR camera couldn't read the plate so it was too small, and yes, he did have a tape measure and did size it up, would have been a £60 fine but let me off with one of those defect notices you have to take to an MOT garage for them to sign then I sent it off.
Go Here:
http://www.platesforcars.co.uk/
You can decide whatever size you want.
I have ordered 203x152 for front & 330x89 for the rear.