Offset versus spacers

[Big-G]

I drive an A6 2015 c7 3.0TDi 272bhp, I have swapped the stock wheels for a set of A5 wheels I had from my last car, the A5 wheels are offset et29 and the A6 wheels are et39, the result is that the stance of the wheels has been widened by 16mm per side. My question is am I right to think that this is a good alternative to fitting spacers? I've never noticed anyone else saying they have done this but it looks great, also myA5 wheels are 18" the same as the A6 but the A5 tyres are 245x40x18 and the A6 ones are 245x45x18 so the overall circumference is 25mm less which lowers the car by 12.5mm. So it has lowered and widened the stance just by fitting the A5 wheels. The only downside is that the speedo will be slightly out but only by 3mph at 60mph. What do you guys think of this? It seems too good to be true.

[Gazwould]

Lowering the offset is desirable and wheels get pushed out , alot of VAG look even with additional 5mm spacer / less offset to the rear , A6 C7 I've no idea .

Is A6 & A5 center bore definitely the same ?

245 45 is a good size tyre , road compliant if not a little bulbous , 245 40 also good and nothing like the stupid low profiles when up sizing to 19/20" ( some confuse and say upgrading , it isn't as there are dynamics to lose with additional weight ! )

You can try to apply maths to tyres but realistically you can't as the manufacturers don't keep to sizes , wider - more grip , slimmer - more mpg , taller profile - more comfort .

This is a rare find which clearly shows a varience .



Your C7 will loose chassis height but gain arch gap with the lower profile .

Best thing to do with regards to the speedo is compare with a downloaded GPS speedo app , as again you can't accurately apply the math .