Hotchkis Sport Anti-Sway Kit front and rear installed this week. Also had the RS 4-2 Blue - Pagid Compounded Race Pads made for the Audi 8pot installed with Motul® RBF 600 in the lines. And I can't forget the most important part, the Potenza RE-01R 275/30/19's. I ran 39psi in the fronts and 41psi in the backs. The tires needed a lap or two to heat up and then the car became totally neutral. Grip was superb with NO under steer, in fact I found that I could use the throttle to force the rear out with a quick lift and it would then snap back in line with a bit of gas. The turn in is now immediate and the car seems to barely lean at all. I found myself able to keep up, not pass but keep up with (No BS) a Lotus Elise. If I had to guess the car feels like it's had about a 40% improvement in handling. I should warn anyone considering this setup that the ride is quite a bit stiffer, in other words you now feel every crack in the road. The cars stock brake pad sensors will also need to be bypassed with any of the Pagid pads. I noticed that I can still catch all four in a redline shift to second but it is now only possible when the tires are cold. I don't know if hardcore is the best way to describe a four door sedan but that is how she now tracks.

I just got the 275/30/19 RE-01R on my car last week and they are absolutely amazing for a street tire. My dealership sure did hate me for trying to get them mounted and inflated. First their machine was broken so it wasnt until 2 days later that it got fixed and they got the tires on the wheels, and then it took 6 hours for them to get them seated and inflated, but all their hard work sure was worth it.

such a difficult mounting procedure with several tries on seating the oversize tire? that would sure be something of concern to me.

It was a real comedy watching a local Goodyear dealer trying to mount the 18" tires on my S4 a few years ago. Recently, though, an authorized Tire Rack installer had no trouble with the 19s on my RS4.

Sounds to me like his dealer didn't have the machine they needed. I can't imagine a place like the Tire Rack spending much time mounting, considering how many mounted sets they ship. But you have to invest in the right equipment. And it isn't cheap.<ul><li><a href="http://www.moderntiredealer.com/t_inside.cfm?action=performancehb_det&amp;storyID=1185">Tire Mounting Article</a></li></ul>

<center><img src="http://pictureposter.audiworld.com/63784/fm2.jpg"></center><p>
I think they're nominally set to about 32, and if you go up to 40 the car loses a lot of grip. Their physics model seems to be a bit off in this respect. Relative changes from the nominal work as expected, but I learned in a hurry not to set the tires to real world pressures.

and the sways have nothing to do with ride comfort. did you check your pressures after a few laps? based on larryv's comments, 39/41psi cold pressures might be a bit high for a starting point.

Bridgestones have tremendous grip, but they are heavy and the sidewalls are very stiff. On my 350Z roadster, I switched from Bridgestone S-03 pole position to Michelin PS2 in the identical size. The difference in ride was night and day.

Stiffer sway bars will detract *slightly* from ride comfort over uneven road surface since they will cause the car to act more like it has a rigid axle.

Bottom line....EVERYTHING is a trade off!!

105 F on the track. I had a 1.3 hr drive up to the track so I never really had a cold tire.

i still worry about going out of spec on oversized tires though.

&lt;&lt; Bottom line....EVERYTHING is a trade off!! &gt;&gt;

so true, Vijay! it has always been and will always be that way.

I've wondered about too wide tires for the rims too. In autox applications you want wider wheels, not necessarily wider tires. Stretching a tire onto a slightly too wide wheel results in a faster responding system with lower slip angles because there is less sidewall flex. Maybe with the latest tire technology that is no longer as important as it used to be. My autox experience is over a decade old now.

close to that?<ul><li><a href="http://www.tirerack.com/a.jsp?a=AR4&url=%2Ftires%2FSpec.jsp%3Fmake%3DBridgestone%26amp %3Bmodel%3DPotenza%2BRE-01R%26amp%3BtirePageLocQty%3D">http://www.tirerack.com/tires/Spec.jsp?make=Bridgestone&amp;model=Potenza+RE-01R&amp;tirePag

there's a reason they specifically warn against exceeding acceptable max tire size per wheel width.

my concern lies with a potential blowout resulting from this iffy mounting method. i mean, tire machines aside, if it took several tries to get the tire mounted where it seats right and holds air, i'd say get it off of there. maybe that's just me though.

you're at the minimum on that range. and, keep in mind, if that's a Tirerack stated range, then take it with a grain of salt. as good as they are(i'm a long time customer), stretching the facts does occur in the industry.

i'm glad you like using the oversized tire, and i hope it works well for you. don't forget the safety factor though.

incidents of this happening where the rim is within the tire's specs? Wouldn't that be a tremendous liability for Tire Rack to stretch the truth?

<ul><li><a href="http://www.bridgestonetire.com/tireselector/SizeSpecs_BS_EN.aspx?Product_ID=1111">http://www.bridgestonetire.com/tireselector/SizeSpecs_BS_EN.aspx?Product_ID=1111</a</li></ul>

but what are the car and tire mfgr positions on oversizing? forget TireRack, does Audi or the tire brand caution against it? i am quite certain they do.

anyway, tire coming off the rim would be a bit far fetched, but blowout or rapid deflation may be a concern, as i mentioned above...when taken into consideration with the mounting difficulty.

the only question that really needs to be answered is whether that size you're running on the RS4 rim is truly approved or not.

i tend to err on the side of caution when it comes to tires and brakes. after all, what can kill you and what can't?

missing your point. Are you saying that it doesn't matter that the tire is going to fit a 9" to 10" rim? You and Audi want a tire that fits exactly a 9" and goes on easy? The fact that the tire fits up to 10" and is difficult to seat is a problem? I have heard that the tire is hard to seat because it is a 30 profile and the lower the profile the harder to seat. When it does seat it pops in place nice and loud, I just don't think it is going any ware. Once again do you have any facts to back up your concern? Without any I just don't know if I should be concerned or not. I transport my wife and two kids in this thing and don't want to compromise any safety issues. I ordered and waited for the rear side air bags just for that reason.

sorry if i'm being confusing. you obviously know the tire you bought and checked it out ahead of time.

however, from past posts here on this very subject, it seemed there was some question about this bigger tire fitting or not. then there have been posts about yeh, it does(eventually), but not without a helluva problem getting them mounted right.

i don't know enough specifics in your case except to advise against going significantly over-size in general, and then to not ignore vehicle safety issues that might result...and, that just because TireRack says it'll work, that's hardly a ringing endorsement.

the fact that it "fits up to 10" should tell you that it is very borderline for the 9" rim, meaning too large. it would be interesting to see how it mounts and seats on a 10" rim.

also, keep in mind that when they have a tire that large, and 10" rims being not very common, then they will try and sell it for the 9" rim fitment, as there are many more of those out there.

finally, what does "fit" mean? yeh, it's actually been successfully(hmmm) mounted on 9" rims so it "fits" 9" rims? not necessarily so.

let me ask you this. when you were having the tires mounted, with all the trouble involved, did any of the tire guys question whether it was the right tire and would fit or not? i'd be willing to lay odds on that one.

sidewall stiffness varies from make to make, tire to tire. you certainly don't want mushy. but you want enough give so that it's not carving up tread in even the mildest cornering.

like the man said, everything's a tradeoff in the end.

fit before I ordered it. They also told me not to worry about the fact that it was so hard to get on the rims. They said they had far worse. I have seen, last week that with modern equipment it takes no time at all.

Why not call or write the Bridgestone customer service department?

if that's the case, then i apologize for doubting this. i guess i should have figured that experienced tire installers would know not to mount a tire that was unsafe.

well, good luck running them. you seem happy with the tires so far.

based on past posts, i was left with the impression that there was some doubt as to the width and spec on this rim.

and that was what i was looking for, something from Bridgestone or Audi about correct fitment of that tire size.

i'm trying to answer your orig unedited post, and poof, it's gone...now, my answer is hanging out there.

Several of us had made measurements and it look like there was going to be plenty of clearance, but you never know until someone actually puts the wheels on the car. I was interested if my measurements and calculations were correct

Sorry about overwriting the other post. It was accidental. It still stands. Bridgestone considers a 9" rim fine for this tire. It's listed right in the specification sheet.

anyway, thanks for the clarification. that sounds more like it.

if it's listed on Bridgestone's spec sheet, then my bad.

Evil, load up the kids : )

check out that S brochure yet? or aren't you that interested? i am in the possession of a real sleeper right now.

as Maxwell Smart would day "and loving it".

The top end Bridgestone tires are known for their substantial grip. That is the good news. The bad news is that they ride hard and are heavy as stink. Compare the 30lb weight for the Bridgestone in 275/30 vs. 25lbs. for the same size Michelin PS2. That is 20 lbs of rolling unsprung weight situated at the location of greatest momentum on the wheel/tire set-up. This is the equivalent of adding about 80 lbs static weight to the car.

Likely the handling benefit is due to the size of the tire and the sway bars. However, nobody that I know of has tried the PS2 in a 275/30 configuration. While the maximal cornering grip may be ever so slightly higher with the Bridgestones, I'm willing to bet that the PS2's will yield a much more responsive car, overall.

In terms of fitting the tire onto the rim, the real problem is the short sidewall with a 30% aspect ratio. A 9.5" or 10" width is really optimal for a 275 width tire with a 30% aspect ratio. The real question is are the sidewalls pulled in so tight on a 9" wheel that the bottom of the tire gets bowed actually decreasing the contact patch ( or not increasing it in any case)compared to a more optimally seated 255 tire. I don't know the answer to that question.

The best solution for this is really to have a light 1-piece forged wheel in 19x9.5 with the proper geometry to fit our cars in about a 19-20lb weight with 275/30 Michelin PS2's. Then add your sway bars, coilovers, or whatever, and you will really take the handling of this car to a supreme level.

The wheel can be done. My Nissan Motorsport wheels on the 350Z roadster are 1-piece, fully forged, 18x9.5" at a weight of 18.5lbs each. And.....the price was $575 per wheel!

Until there is a good option for this, I'm staying stock.

i agree totally with your comments.

when going out of spec, or even out out of OEM, the downside should always be considered.

not to say that it shouldn't be done in some cases. but, you can't just ditch stock items and then expect miracles. there is a reason the cars don't come like that from the factory...they strive for a happy medium between all out performance and balance, comfort, durability.

in a discussion, make a mistake...just erase it, walla!

there's not enough weight back there to flatten out a tire that wide at that PSI. so you're running on the center of the tire. i bet dropping all will yeild the same oversteer but higher ultimate grip levels. you want to increase front grip instead of decreasing rear grip to get oversteer. this is where the lower lap time will come from.