Currently Sport package with 17 inch wheels/tires. Considering OEM 16 inch wheels to get softer ride. Read in another forum (2-3 year old post) that you should never put the 16 inch wheels on the 4.2 because overloaded, and Audi has discontinued that wheel for the 4.2. Any thoughts, comments?

 

Car's base wheel was a 16" at introduction--16x8, six wide spokes, with a 235 tire. The brakes are sized to allow down to 16's. Audi probably discontinued it because so few were sold w/ 16's, and to differentiate it better from the V6's.

The argument about overloading sounds upside down too--typically it is a lower profile tire which has a load problem, not a higher profile tire, even if the width decreases some (which tends most to then expand the front to back footprint). I think that argument goes out the window when you consider D2 A8's were sold for years with 225's in a similar weight vehicle. C4's were sold with 195's on a 7" rim, and a C4 weighs almost what a C5 4.2 does. I've owned 'em both... The better argument is actually the outside of the brakes might get hot with more restricted air flow, but for normal street I really doubt it; the HP2's and related disks are sized for Autobahns after all, not just US snail traffic.

If you want a somewhat softer ride, instead try:

1. 255/45's on the 17's instead of 255/40's. Fills up the wheel wells nicely; adds a 1/2" of sidewall, which is exactly what you get with dropping down to 16's. The bigger diameter nets to what was used on the RS6, so Audi decided it was okay.

2. If you have a sport suspension, change the front roll bar to the non-sport version. Having started with a non-sport, I wouldn't change the rear--it literally makes passengers motion sick (beyond Buick...) if you drive it with any spirit. If you have H sports on it by chance, backing off to a set of sport bars, or even a non sport in front will soften it up.

 

While there no problem with overloading as long as you use the correct tire size (225/55R16) there are not many 16" wheels that fit over the large brakes on this car.

We have only three that clear. They are listed under the winter section of our site.<ul><li><a href="http://www.tirerack.com/a.jsp?a=AR8&amp;url=/winter/index.jsp">wheels/winter</a></li></ul>

 

would the 225/55/16's or the 255/45/17's give the better ride (currently 255/40/17).

 

The 235/50-16 OEM tire had a load rating at least equal to the 17" size. But do bear in mind that 235/50-16 is an oddball, hard-to-find size. Check the tire rack's site to see what I mean. The next size up, whcih clears just fine, is 245/50-16 which is + 2.5% on circumference. I run this combo. Heavy but otherwise nice.

This yields a 97 load rating - far from being overloaded, it in fact gives you a huge, over engineered cushion. Very little will bend those rims nad tires!

Another alternative that works well is 16 x 7.5 (more available) with 225/55-16. This gives a load rating of 95 in most applications - again hgiher than the 94 of the 17" 255/40-17 whcih came in the sport option, and on S6 avants of the same era.

Grant

 

..but I agree with you that the 225/55-16 is a better size, especially for the winter. I run them.

Grant

 

First, I think some of the replies are mixing in other C5 bodies and also winter type sizes. I am answering assuming you have a C5 4.2 sedan with the fender flares. If so, Just Me has the correct OEM size in his newest post, albeit rare, at least per the manufacturer's sticker on my 2000 4.2 that I bought new.

Yes, a 225 will give you a softer ride almost certainly in a 55 sidewall, relative to a 255 in a 45 sidewall. But, parsing the words carefully, note I say "softer" rather than "better." When you check into it I expect you will find even accounting for the inch stepdown in rim size, that with a 55 you are adding a pretty fair amount of sidewall in there. Yes, it will soften the ride, but you will feel it in the handling as a loss in precision and somewhat less direct feel. Maybe more importantly, I expect you will give up a good amount of brake performance. On the 4.2 with HP2's and 13"+ front rotors, I think the limiting factor is traction even with 255's. Inevitably I think you will be giving up some stopping distance when you take that much out of the width equation. Essentially you are going back to a 2.8 type tire size, and I don't think anyone will seriously say a 2.8 stops at nearly the level of a 4.2, both because of the brake system and the tires. Besides all that, I think a 225 type tire on an 8 inch rim on a car with aggressive flares is aesthetically just not the best to say it mildly. You might increase the MPG a tad, but I don't think thats why folks buy a 4.2 to start.

Yes, you will soften the ride a notch still with the 255/45's. You'll give up a bit in handling and little if any in brakes. Also if you are by chance using a summer tire, you may also soften it up some with a good all weather tire. Finally, knowing the car, you can tweak it a fair amount as far as apparent ride stiffness with the roll bars. If you have 17's on a 2002, I would venture to guess you do have a sports suspension. Changing the front bar in particular is easy, would cost you a fair amount less than a used set of rims and would have some effect. If you post on the C5 board, there are probably more than a few non-sport and even sport bars gathering dust all over the country where they were swapped out for HSport bars.

Finally, what tire pressure are you running? If more than 40psi and you want a softer ride, I would certainly back it off to that.

 

255/40/17's on it and am looking for a softer ride (although I've had the car for 6+ years, so I don't know why I am just getting to it now!) It sounds like I should be looking at 255/45/17's to ride better without giving up much in handling/braking.

 

245/50-16 GSD3s (8" rims)

winter Dunlop M3 225/55-16 ( 7.5" rims)

Works great. Does more sidewall mean mroe flex? Of course. IS that an OK trade-off? I think so. Then again, I have a pure sports car for those occasions.

Grant