swapping wheels for a different size

[Chris 1971]

Hi,

I have an A4 Avant 2012 S-line Black edition, TFSI. Owned it for about 8 months. It has 255/35 R19 rotor-style wheels/tyres. I like the look of them (and I have kept them absolutely pristine), but the car suffers quite a bit from tramlining. Everything else seems to be sound, the wheels are shod in Michelin PS3s and I've not heard that these tyres are particularly prone to tramlining compared to other tyres (quite the reverse it would seem). So I'm assuming it's just a characteristic of this specific wheel/tyre size.

Despite them being head-turners, I've begrudgingly come to the conclusion that I place more value in the cars handling than it's looks (where they are mutually exclusive). I've got the option of a set of used 245/45 R18 s-line wheels (the 10-spoke ones - from an A6 I believe), plus tyres. They're in very good condition and the mid-range tyres still have about 6-7mm of tread. I can get them for a very good price (about half the price of 4 new Michelins on the 19s...)

The 19s are due new tyres in the next 3 months or so.

My main question is: can I just slap the 245/45 18s on in place of the 19s? simple maths says I can (I think), but am I missing anything? I've been told that I can from someone supposedly in the know, but I want to 100% sure, and be aware of all implications.

If I can just swap them, I'm tempted to get the 18s with the deeper profile tyre, which should hopefully improve the tramlining. I'll store the 19s until I flog the car in 2 or 3 years time, and then put them back on, at which point they will still be in perfect condition and should be a big selling point at that time. 

I'd be grateful for some pointers from the experts on here, specifically in respect of the points highlighted in bold above.

Many thanks,

Chris.

[Steve Q]

Hi Chris, yes they should fit but you'll need to have your tracking done afterwards. 

Cheers

Steve

[Chris 1971]

Many thanks Steve. Yes, assumed i'd probably need to do that afterwards.

[Magnet]

Hello Chris,

I too follow your logic of increasing the profile of replacement tyres to attempt to replicate the final tyre diameter of your current 19 inch wheels. Why owners strive to run their cars on such ridiculously low profiles remains a mystery to me, unless they constantly drive around corners on two wheels!  The ride comfort must be compromised, and Dunlop - bless him- worked hard to develop pneumatic tyres for us, as replacements for the original solid tyres. Need he have bothered? 

What I would ask Chris is, were the intended 18 inch replacement wheels a factory option for your model? If so fine, if not, you would be wise to pass this intention passed your insurers before committing. 

Apologies for having a varying opinion, but I cannot see a need to check the wheel alignment,  if the current tyres are wearing  properly. 

Kind regards,

Gareth.