TIRES - A6 4.2L - 255/40 R 17 v. 245/45 R 17

[Miggsman]

I feel silly asking, but does anyone have strong opinions re: tires on a 2003 A6 4.2L? I am changing my originals at 60,000 miles. Original tires are Continential Extreme Contact BSW 255/40R-17. However, the salesman at Discount Tires claims I'd be better (or at least just as good) with Extreme Contact BSW 245/45R-17. Salesman claims I don't need the extra 10mm in width and that the increased profile will better suit the ride. I'm hesitant since 255/40 is what came with the car - anyone have an opinon? Am I wasting brain cells caring? Thanks for your time.

[Audi42LV8]

I have 245/45 17R on mine.

[Press]

either one is fine

[JimtheDentist]

The 45 series sidewall may give a slightly smoother feel. Do you have any issues with your present ride quality? if not, stick with what you've got.

I tried 255/45/17's in an attempt at a smoother ride (yes, speedometer was off 2-3%.) No noticeable change in how if felt to me, so I 'm back to stock configuration.

Jim
a6-4.2/S6-avant/rs6

[Miggsman]

Thanks for the responses.

I followed the tire guy's advice and went with the 245/45s.

The ride seems smoother, notably over the many speed bumps I pass daily.

I noticed some squeeling when taking sharp turns where there wasn't any noise before...

Ultimately, I don't feel a valid comparison is possible since the old 255/40s were worn and the new 245/45s are not only new but also siped.

Thanks again for the input.

[Just Me]

And plan to do the same someday on my S6.

It will also result in fewer bent rims if you live in an area with bad roads, like, say, planet earth. Or at least anywhere above the frost line.

G

[skapan]

I know there's not much difference between the sizes, for that reason alone I would stay stock. Maybe the 245/45/17 was not available when the car was designed, but you should be on the 16 inch wheels if you want a more compliant ride (stock on C5 4.2 back then).

[skapan]

Another thought - does the 245/45/17 meet the load rating requirement for the car? I know that's a real problem for a lot of the tires available for my C6 S6.

[Just Me]

And when i answered above, it was not from ignorance nor just a wild idea. I researched the sizes, nad the load rating is higher on the 245/45-17. Substantially. Note that load rating is a good (although imperfect) measure of how much a tire can withstand in an impact without deforming to the point of rim/road contact. So it will certainly, not might, will - protect your rims better.

Is 16" better still? Yep. And guess what? I run them 245/50-16 - load rating 97 baby. Kenworth territory. But they are nto for everybody.

But the incremntal increase is clearly worthwhile, both in protection and in ride. If you go to 16, you will lose significantly in terms of sidewall steering response - although a top notch 16" tire will still outperform a crummy all-season 17.

Also ntoe that the OEM size, 235-50-16 for all practical purposes does nto exist. try to buy them. 30 year old designs like the P6 all season. Goody.

I bent a couple wheel son my S6 in stock size. I then bought replacements that turned out to be bent. (alas, from someone on this very forum who swore they were straight, took my money, then ran away when confronted with the truth, sigh). From thsi we can deduce that Audi blew it on the sizing, givent he car's front weight bias and very stiff suspension. if you dont understand hwo this all inter-relates, do the math. It does.

Best of luck. I stand by my suggestion.

Grant

[Miggsman]

I certainly didn't do the research that Grant did. I will, however, corroborate his opinion by noting that the my reason for changing tires is that my wife struck a pot hole with the 255/40 17 tires and bent a rim and put a bubble in the sidewall.

I'm glad to hear this is less likely with the 245/45 tires.

Also, the 255/40 17 tires were stock on the 2003 4.2L with the 17 upgraded wheels.

Thanks again to everyone for the input.