...15" may be too narrow so would look at spacers and lowering...
Smart 15" wheels most definitely would be too narrow for normal driving,
and spacers or lowering would make little if any difference to the level
of grip or handling
in normal weather conditions and would quite frankly
be so completely different to the point of being woefully inadequate.
TBH, it would take very little to spin up 15" wheels under normal driving
conditions in a 454 Brabus, no matter if you had spacers or if it were
lowered even more than it is as standard.
However, you are considering these 15" for winter...under the assumption
that at some time in the near future the weather where you live in the
southern part of the UK (below Manchester) will no longer be as mild as it
is or has been over the last 10 years.
Most 'enthusiasts' are aware, rallye car use skinnier wheels and tyres on
loose snow and ice as the specially grooved and spiked tyres 'cut' through
that better than any normal wider road tyres. But you are not rallying your
Brabus, so I tend to agree with JJ and say that 16" Colt CZT wheels would
be the smallest I would fit...to balance the power to grip ratio. And for winter
conditions of consistant snow with some ice I would have them shod with
either 'full house' winter tyres, or....if you live in the 'warmer' southern part
of the UK, use 'all season' tyres from the likes of Michelin.
(Michelin tyres are however not that cheap)
