I’d suggest you go for a drive in a Leon that’s fitted with 15” wheels first to see if you notice any discernible difference in ride quality between 15” and your existing 16” wheels before investing in a set of new wheels and tyres. I doubt there’d be a massive difference in ride quality.
If your existing wheel / tyre combination is 6.5j x 16 ET46 with 205/55 R16 tyres, then fitting 6j x 15 ET43 will result in the following clearance differences;
- increased clearance of 9.4mm between suspension strut and inner wheel face
- front face of wheel will protrude outwards 3.4mm less than your current wheels
With a 6j x 15 wheel with an offset of ET48, the clearance differences compared to your existing wheel / tyre set up will be;
- increased clearance of 4.4mm between suspension strut and inner wheel face
- front face will protrude outwards 8.4mm less than your current wheels, which in my opinion could look a bit odd as the wheels might look ‘lost’ and hidden under the wheel arches.
You’ve said that the 15” wheels with the less aggressive (ET48) offset are cheaper. Depending on how cheap they are, cheap might equal poor quality - either in terms of the structural integrity of the wheel or the quality of finish. They may also not have been subjected to the stringent safety / quality testing (TUV, ABE, JWL or equivalent certification) that wheels produced by well known reputable wheel manufacturers. If considering buying used wheels, always check that they’re not buckled or cracked or have had structural
repairs.
Also bear in mind that changing your wheels would be a vehicle modification for insurance purposes, so you’d need to inform your insurer, and they might charge you an increased premium.