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Hi all,

Just been offered a set of bridgestone 255/40 19's cheap off a breaking S8. Will the difference in profile be a problem?

Any advice on this guys?

Tyre sidewall will be about 13mm more on the 40 series, which is a fair amount. If you're running standard height suspension then you'll probably have clearance - if you already run aftermarket stuff and are already lower, then you might get wheelarch rub. But overall you'll not really notice the difference as far as I can see. Outside chance of rubbage on full lock though, which is comment-worthy at most I feel.

But the most important thing is to check the Speed Rating and Load Index is right for the car - spec says 96Y XL (Extra Load) for the OEM tyres and you'll need to stick to that ideally.

Tyre specs are critical to handling and more importantly to insurance companies. Not worth the risk of getting it wrong IMHO.

Phil G

People probably haven't answered because they're not too sure.

The best I can do is offer this link which will graphically show the difference between whatever you have now and the tyres you are proposing.

Link: http://www.carbibles.com/tyre_bible_pg2.html

Scroll down to the 'Tyre Size Calculator' and enter details for old vs new.

Comparing oem (255/35/19) against your proposal (255/40/19) results in a circumference difference of 3.86%. So when you're doing 70mph, you'll actually be doing 72.7mph.

'Spacecowboy' recently had rubbing issues with what turned out to be an oversized tyre so I'd be very wary fitting the ones you propose as they are certainly oversized compared to oem and could rub.

The only way you'll truly know is to go to a tyre fitting station/garage and have them fitted and check for clearances there and then, though this will obviously cost money - but would be by far the safest option (better to be safe than sorry).

Sorry this isn't the simple answer you probably seek, but previous posts on wheel/tyre combo's have given hugely mixed results - some good, some bad and some dangerous.

There are people on Audiworld forums that are running 20" wheels etc. on RS6's so it might be worth posting on there to get more/better info., however a quick calculation shows that the 255/40/19's are still bigger than even 275/30/20.

Whatever you decide, it's imperative that you do all 4 at the same time as the diffs/transfer/gearbox will be trashed if the rolling radii are mismatched.

HTH.

MORS6+ wrote.......'' Comparing oem (255/35/19) against your proposal (255/40/19) results in a circumference difference of 3.86%. So when you're doing 70mph, you'll actually be doing 72.7mph ''

Fitting larger diameter tyres might just make his speedo even more accurate at 70mph since they are usually optimistic anyway, one way to check would be using an aftermarket portable sat nav I think !!!!

And acceleration might also suffer under 80mph after that the larger diameter should be a little quicker not that you would normally notice it on the road.............

Personally I would not put these on my car. You do not know what sort of treatment they have had and TBH putting worn tyres on an RS6 is in my opinion, crazy. Its the only thing that keeps you on the island, and one thing i would never cut corners on.......