When the GP first came out there was quite a few stories in here about problems caused by fitting 17" wheels on the 1.2, something to do with the lower power / extra torque involved putting extra stress on clutch & gearbox due to having the extra effort involved getting the car moving from rest...
It may be that the ones affected were driven "energetically"... I have no personal experience of the li'l GP, but it's the OP's car to do with as he pleases!
Here's a Thread to read through if you missed it before... from late 2009...