Assuming the bolt pattern (PCD) is 5x112 on your Leon wheels, and the centre bore is 57.1 for both your current wheels and the VW Madrid wheels, then they should fit. Your existing tyres should be OK too; according to the VW brochure at the link below (page 16), tyres used for the Madrid wheels are 225/45 R17; i.e. same as your existing tyres. You just need to check that your existing wheel bolts are suitable for use with the Madrid wheels, as wheel bolts come in three different types - tapered, rounded or flat - and it's really important that the mating surface of the bolt head is the correct profile to fit the profile of the bolt hole in the wheel.
With the Madrid wheels being 7" wide and an offset of ET49 compared to your current wheels (7.5" wide and an offset of ET51), this will give you 8mm more inner clearance, and the face of the wheel will be tucked under the wheel arch 4mm more than with your current wheels. You can check this by using the wheel offset calculator at the 2nd link below;
How did you establish centre bore size of 57.1?
What's best way of checking the correct type of wheel bolt style for Madrid?
Cheers mate.
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