As a cheaper option, if you are only concerned about revs at high speeds and less about high speed cornering , then going to a higher profile tyre will have a similar effect with less hassle, although you will have to confirm using GPS as speedo will still record as before.
Actually both my winter and summer tires are bigger than recommended my summer tires are low profile 205 on 17 inch wheel winter are 225 on a 17 inch rim and yes it does affect the Speedo because on the Speedo I see 140 Km on the gps it says something around 129As a cheaper option, if you are only concerned about revs at high speeds and less about high speed cornering , then going to a higher profile tyre will have a similar effect with less hassle, although you will have to confirm using GPS as speedo will still record as before.
There are websites that give speeds at different "rolling circumferences" with different tyre or wheel combinations.
Tyre clearance can sometimes be a problem and you will reduce your acceleration, so your choice.
I don't have any gearbox data, maybe others on Forum can advise.
The other thing I noted was the T jet in some data I saw had max revs around 5000 compared with 6000 on the more basic 1.4 16 valve and there appeared to be an option of 18 inch wheels, so all those things will give gearing change requirements.
