[Albertz03]

Guys, 1st time here, advise please if possible? Just got a F10 520d with Factory 17" Alloys in rubbish condition so been offered F30 18" as upgrades.

Will they fit as i'm told they're a straight swap?

Thanks in advance.

[Johnny Grabble]

The alloys are similar in size and offset:
F10 17" are a square set up 17 x 8J ET 30 with 225/55 R17 tyres with a 5 x 120 bolt pattern.
F30 18" - if they are a square set up, some sets are staggered - are 18 x 8J ET 34 with 225/45 R18 tyres and the same bolt pattern.
If you were to use the F30 wheels, you'd need to change the tyre size to 225/50 R18 to get the same rolling radius. I don't think the different offset makes a meaningful difference.
I think that's correct but it's down to you to check and verify at your own risk before you splosh the dosh.
Willtheyfit.com is your friend.

[Albertz03]

Thanks Johnny.
I double checked with an online alloy retailer and they confirmed they will fit so thanks again for your time and detail