If your new alloys are from a reputable alloy wheel seller such as Rimstyle, Wheelbase Alloys etc., then they should provide a fitting kit which will include all that you need (bolts of the correct type / size and spigot rings if required) to mount the new alloys on your car.
If they’re aftermarket alloys (with an offset of ET41, they probably are aftermarket rather than OEM), then most aftermarket alloys use bolts with a tapered seat (bolts for OEM alloys usually have a radius seat). It’s really important that the correct type of bolts are used to ensure maximum contact and a snug / tight fit between the mating surface of the bolt seat and the bolt hole of the wheel.
If your car has a space saver spare, if you do need new bolts for your new alloys, be sure to keep a set of your existing wheel bolts in your car to use with the spare wheel.
Bear in mind that aftermarket alloys are also likely to have a centre bore that‘s larger than the 57.1 centre bore size of Seat OEM alloys. Therefore, you’ll need a set of spigot rings of the appropriate size to reduce the centre bore size of your new aftermarket alloys to 57.1 to make it easier to mount the alloys and ensure they’re correctly aligned on your car‘s hub assemblies. Spigot rings should also
help eliminate the risk of vibrations and imbalance.
I wouldn’t have thought that an extra 16.4 mm of poke would cause any tyre rubbing issues. However, you can do a visual check by measuring out 16.4 mm from the face of your current wheel / tyre to see if there’s any risk of the tyre fouling the bodywork (assume your car is standard ride height and hasn’t been lowered). Also, it’s important that the overall rolling radius of any new wheel / tyre set up is the same as (or as close as possible to) your existing wheels / tyres - if not you’ll experience speedo reading errors. If the wheel calculator you’ve used doesn’t give this information (i.e. existing and new rolling radius), then the one on
www.willtheyfit.com will.
Lastly, fitting new wheels is a modification for insurance purposes, so be sure to inform your insurance company.
