You are so right. Too much red wine last night. 5mm diameter is less than the difference in tread between a worn and a new tyre.

either way, can't see the difference having much of an effect on fuel economy

can't see the weight of the wheels making that kind of difference either - mk4 Cupra alloys weigh about a tonne each, yet my Ibiza can still get 400+ miles to a tank so long I'm not driving it like a tool all the time

either way, can't see the difference having much of an effect on fuel economy

can't see the weight of the wheels making that kind of difference either - mk4 Cupra alloys weigh about a tonne each, yet my Ibiza can still get 400+ miles to a tank so long I'm not driving it like a tool all the time

Agree completely.

No mention of checking your tyre pressures are correct yet, I'd suggest that

Just to throw one in here,

my Octavia vRS with heavy 18" R32 Reps on got better MPG (around 4-6mpg)than it did with the 18" team dynamic Pro Race 1.2 lightweight rims.

As said before, once up to speed it will take less to keep them going. the OP says its short town driving so a lot of stop start, then the lighter the wheels the better there, for Mways where speeds are constant then a heavier wheel would be little different if not slightly better.

I am getting so far around the 55mpg mark in the Fabia vRS with std rims, I am pos going to use my 17" spiders for summer wheels with 205 40 17 tyres as I dont need them for the Octavia vRS as I have the LCR 18" rims.

will be good to see what the weather does to your MPG.

OH and I have found that both my cars dont like the wet, it drops the Octavia mpg down by about 3mpg and the fabia down by 4-5 mpg.

Best is dry clear nights but no frost. if its too cold it drops too.

i have my vrs on 17s and still get 40ish mpg round the town and can get to 57 mpg on a run on the motorway