Minor/Midget drag/gearing/tyres

[Mr. V]

I've been pondering gear ratios and tyre sizes for my 1275 Midget engined car and have decided that in spite of the assumed difference in drag between the Midget and Minor that it would be best to adopt the same overall top gear ratio as the Midget.

The Midget has a 3.9 diff and the standard tyres are 145/80 13s.
According to my calculations the Minor's 4.22 diff combined with 155/80 14 tyres would give an almost identical overall ratio.

My present set up is, by the way, 3.9 diff and 165/80 14 tyres which seems painfully slow to get up to speed, especially given the few motorway miles that I do.

So, am I barking up the right or the wrong tree? All contributions gratefully received.

[Chipper]

My 1970 Minor Traveller also has a 1275cc MG Midget engine, and 165/70R14 tyres. I tried fitting a 3.9:1 diff, but also found it to be a bit too tall geared and ponderous going up the steep local hills, so I reverted back to the standard 4.22:1 diff, which gives a good overall responsive feel, if a bit busy on motorways.