low mpg ?

[pumamc]

i've had my 182 a year now and the mpg has hovered between 29.2 and 29.8 but i had really rubbish tyres oput on when i upgraded to 17's. now i've put decent tyres on and mpg went up to 31.7 but now its dropped to 28.5 ! whats going on ?
mel

 

[Sy]

pah feck all, try 23.8 on 17's lol. Plus I think my exhaust is a little suspect

 

[Ja5on]

nothings goin on!!! its all normal, weather conditions change fuel consumption, where ur driving etc etc

 

[pumamc]

cheers ! wondered if it was the 17's
mel

 

[DrR]

To many variables. sounds about right though.