As per ECE R$117,$ at what speed, the tyre rolling sound is measured for M$1$ & N$1$ vehicles with Class C$1$ Tyres $?$

Question $22$Answer

a$.$

$20$ km$/$hr$$

b$.$

$100$ km$/$hr$$

c$.$

$50$ km$/$hr

d$.$

$80$ km$/$hr$$