You won't be saying cool when you have to change 2 wheels when you are stressed out in a hurry and changing a wheel in the rain or dark with the crappy standard jack and the wheel nuts torqued at a million nm! Flats never occur in easy situations it seems! But he has a sport and the spare is obviously standard so it's okay
Driving with one 16 on at the mo feels a bit weird and uneven how come people are saying this is fine?
Using a tyre size calculator, it would seem that your new wheels with tyres (assuming you're running 205/40 R17) will stand 0.2" taller than stock, meaning the hub will sit 0.1" higher from the ground than it did as standard.
This means that with the old spare on one corner of the car is 0.1" lower - to be honest I'd be amazed if you can actually feel this - I'd imagine it's more likely psychological - because you know the spares on and it's a different size you think it must feel odd
Ive been told not to even put the spare (16") on, as its not safe for long distances etc! Some people say its ok and others say not 2 even bother lol
As long as the tyres are correctly sized to give as close as possible the same rolling radius, then you'll be fine.
My old Fiesta came with 15" alloys and a 14" spare as standard - no
problem there.
My A3 has 16" alloys and an 18" space saver spare - again no problems as the rolling radius is matched.
It's probably advisable not to run over 50 mph or for longer than say 50 miles (as is normally advised in the manuals of cars with mismatched spares) as if there is a slight difference in rolling radius the resulting difference in rotational speed will confuse the ABS system causing a fault to be logged.