Section 77(2) in The Central Motor Vehicles Rules, 1989
(2)The registration mark shall be in English letters and Arabic numerals and(i)save in the case of a motor cycle or an invalid carriage, the letters shall be not less than 6 centimetres high and 2centimetres thick at any part, the numerals shall be not less than 9centimetres high and 2 centimetres thick at any part, and there shall be as pace between any letter and any numeral and between any letter or any numeral and the edge of the plain surface of not less than 1 centimetre and a space between any two letters and between any two numerals of not less than 1centimetre; and(ii)in the case of a motor cycle or an invalid carriage, the dimensions of the letters and figures shall not be less than two-thirds of those specified in clause (i).
