Ok,

maybe the middle of the night is not the right time for questions but... does anybody know what are the max. dimensions of the tyre that can be fitted and safely driven on an 8-year old Fabia MPI?

VRS had 205/45 16 tires, can a "common" MPI handle such a big wheel? Or a 205/50 15 tyre, acctually?

Because, I've just fitted the 205/50 15 tires on my girls Fabia and now some friends got me concerned that it could hit the car body on bad roads, in turns... especially when carrying 5 people and a heavy load. Is there enough space for a 205/50 15 wheels beneath the hood of an MPI?

With one or two persons in the car - for now it fits and rolls just fine, but... can a heavy load or a bumpy road change that?

The answers to all your questions are probably here http://www.carbibles.com/tyre_bible.html where there are also calculators to determine tyre sizes of appropriate rolling radius compared with standard. With the tyres you have the rolling radius is reduced, therefore the speedo is over-reading, so no chance of being caught for speeding unintentionally.

Heavy loads and bumpy roads can potentially cause tyres to rub when otherwise they don't. Also check carefully the inside of the tyre is not rubbing against things such as the suspension strut. Care needs to be taken with the wheel offset measurement and tyre width. More care needs to be taken if you have lowered the car.

I've got 205/40 17 tyres with 70mm+ drop and no rubbing even fully loaded.