i still trust gps... so if the meter reading is taken from gearbox ratio... when we change the tyre, for sure the reading will change...
for example for r15 the circumference is 1 meter... but when ive change to r16... maybe the circumference will be 1.5meter...
so, if the meter only read gearbox ratio, that is number of rotation of the tyre...if r15 one wheel rotation the distance will be 1meter...if change to r16, distance will be 1.5m.
for sure the reading will change... when the km/j meter "lari"...
for sure mileage pun lari.... let say im running at 60km/j meter reading... after 1 hour, the distance ive gone is 60km at mileage.
yet, the real thing is, gps reading showing 65km/j, n the distance ive cover is 65km...
so, thats why im asking...

yup.. but for ur info.. mileage reading is just for our info how long have we running our car due to maintenance reminder or for us to know how long our journey have gone.. of corse its have +/- for each car mileage reading.. if u want a perfect distance.. just try change ur tyre size, then see the km/j reading.. the right set up tyre size will be the same speed as gps but u need to try many size of tyres.. when u get the same speed with ur gps that is the best result.. so u can keep the size of tyre..