8.5 to 9.5 width on same tire question....

[407guy]

(Yes, this is posted in the tire & wheel forum but I'm not sure on the traffic there so I'm giving it a shot here....)


Here is my question:

We have the 19x8.5 +35 wheels on our 2013 S4 (B8.5). Tires are 255/35-19.

We like the look of the sidewall (height) and how it “fills” in the fender gap. [Sorry, only way I know how to describe it.] We aren’t fans of the actual OEM wheel though.

If we went with a 19x9.5 +45 offset wheel and kept the OEM tires (255/35-19), how much will the “stretch” lower the sidewall height?

I hope I’m describing what my concern is.

We just don’t want to go with a wider wheel with the OEM tires and make the combo look “lower profile” since the tire has to stretch to fit the 9.5 width.

8.5 to 9.5 has got to create some visual differences, no?

Thanks.

[C-5Hvy]

It will have a minor stretch, if you look in the modified wheel and suspension thread at the top of the forum there are a ton of pictures in there. Some people dont mind the minor stretch and it will help avoid rubbing the fender, but some people hate it. It also depends on the tire you put on the wheel. Michellin tires are more square with less visible stretch for a 255 while others are not as square. If you go on tire rack and click on potential tires for your rims it will give you all of the dimensions (tread width, contact patch all that stuff) and you will see that some are slightly bigger than others sometimes by up to .5 inch.

There is also another thread floating around about putting 265's on a 9.5 wheel, do a search.

[407guy]

Thanks. I have been looking. My challenge is most have (1) dropped the car so I don't know how 9.5 will look on factory height and/or (2) that thread doesn't always list the specs -- wheels and tires. Nothing you and I can do abotu (2), just isn't helpful for me.

[13S4]

Stock is 19" wheels are 19x8.5 ET 43. Not ET 35.

[zcd2.7t]

8.5 to 9.5 has got to create some visual differences, no?

Thanks.

Yes - ask and ye shall receive....

Here's a 255/35/19 Michelin Pilot Super Sport on the OEM wheel:



And here's the same tire on a 9.5" wide VMR 710 wheel:



Not only did I not like the looks of the tire on the wider wheel, but the performance would have likely been compromised, too, due to the sidewall and shoulder tread blocks not being oriented in the way that Michelin intended.

I sent the 9.5s back and got 8.5s instead.

[mr_coo168]

Stock is 19" wheels are 19x8.5 ET 43. Not ET 35.

19x8.5 et 35 or 40 dropped on oe springs which one would be better would i be rub free with et35?

thanks

[407guy]

Stock is 19" wheels are 19x8.5 ET 43. Not ET 35.

Really?

I've been reading all over the place that it's 35.

*shrug*


We have the "5-segment-spoke-design alloy wheel with 255/35 summer tires". (Taken from audiusa.com.)

[407guy]

Yes - ask and ye shall receive....

Here's a 255/35/19 Michelin Pilot Super Sport on the OEM wheel:



And here's the same tire on a 9.5" wide VMR 710 wheel:



Not only did I not like the looks of the tire on the wider wheel, but the performance would have likely been compromised, too, due to the sidewall and shoulder tread blocks not being oriented in the way that Michelin intended.

I sent the 9.5s back and got 8.5s instead.

SOLID!

Thanks for the pix. That is our concern too, how much handling may be compromised.

And also how much of the wheel lip is exposed for damage/rash. I've read how guys have bent wheels with normal everyday driving after stretching a tire to fit a wider wheel.

[jfabes]

1) you won't see the stretch looking at the car from the sideas it deosn't change the wall height really (profile), you would only see it looking from the front/back angle wrt the rim edge. 2) 99% of people have no idea what a small amount of streth looks like (and this is really small), so unless you have the two back-to-back like above, it will go unnoticed. 3) you will never see the effects of handling on the street even if you push the car hard. take it to the track...maybe...but still have to be a skilled driver to discern the difference. there are way more important things to cconcern yourself with for tracking than this small amount of stretch, i.e springs, shocks, sways, end links, AK, etc.

[13S4]

19x8.5 et 35 or 40 dropped on oe springs which one would be better would i be rub free with et35?

thanks

I'm pretty sure the stock 18's are 18x8" et 35?

[staticuxo]

1) you won't see the stretch looking at the car from the sideas it deosn't change the wall height really (profile), you would only see it looking from the front/back angle wrt the rim edge. 2) 99% of people have no idea what a small amount of streth looks like (and this is really small), so unless you have the two back-to-back like above, it will go unnoticed. 3) you will never see the effects of handling on the street even if you push the car hard. take it to the track...maybe...but still have to be a skilled driver to discern the difference. there are way more important things to cconcern yourself with for tracking than this small amount of stretch, i.e springs, shocks, sways, end links, AK, etc.

this. those PSS 255 on a 9.5" is BARELY stretched. it will NOT affect your handling negatively in any way. 255 is perfectly suitable AND in the manufacturer's range for a 9.5" wheel.

[407guy]

Understood but a picture is worth a 1,000 words.

See zcd2.7t's pictures above...

Just my preference to stick with a 8.5" width.

[lmwong]

Really?

I've been reading all over the place that it's 35.

*shrug*


We have the "5-segment-spoke-design alloy wheel with 255/35 summer tires". (Taken from audiusa.com.)

That's the tire sidewall height, 35, not the ET, which is 43.

As I've been looking for wheels myself, I've found this calculator to help me out. Stock peelers are 19" 8.5 ET43. Stock wheel is 255/35/19.

[staticuxo]

Understood but a picture is worth a 1,000 words.

See zcd2.7t's pictures above...

Just my preference to stick with a 8.5" width.

well aesthetics are subjective, haha. looks good either way! the very slight stretch will allow you to push the wheels out farther giving you a more flush look, which i am a fan of.. but i also love a nice meaty setup!

[MMisencik157]

I have been been tracking/competing in time attack events in my S2000 for a few years now. Ive been able to test quite a few different setups and would like to believe Im pretty knowledgable on the subject. Im seeing some misinformation in this thread. To be clear, running a wider wheel (to an extent) for a given tire width actually increases its performance, not decreases. So dont confuse stretching a proper tire width with the crap that the "stance" or "hella flush" crowd do

There are many reasons to run a tire slightly stretched for performance related reasons. Im too lazy to type my own explanation so Ill steal one of Emilio Cervantes' (Owner of 949 racing/NASA record holder at many tracks in California). He stated, "Lateral acceleration is only produced when one or both sidewalls are under tension. You turn the wheel, the contact patch lags behind as the sidewall winds up and tensions. With a wheel tire combo that allows the casing to roll back and forth or the tread area to twist relative to the wheel centerline, you have some lag time before there is a change in the vehicle's lateral acceleration. Widen the wheel to the point that both inner and outer sidewalls are always in optimum tension and you reduce the time needed for any steering input to effect a change in lateral acceleration. So quicker and more linear response turning in, making corrections mid turn, throttle inputs, etc.

The greater air volume from using a wider wheel allows lower air pressure to carry a given load. This lower air pressure allows the tread and sidewall to more easily conform to irregularities in the pavement, which increases grip.
The spring rate of the tire is also slightly lowered. This lower tire spring rate can be good or bad, depending if the tuner has compensated for it with in tuning everything else. The combination of spring rate and more deformable casing can allow a properly tuned suspension to reduce contact patch load area variation. That's the tiny little fluctuations in loading on any given part of the contact patch. Ideally, you want the contact patch loading always right at optimum to achieve maximum grip. In exaggerated terms, that's skipping across the pavement or smoothly rolling/sliding.

If you have any experience testing radials, you will already know that they will be fastest on a wheel roughly the same width as the casing, not tread. This does not change with sidewall stiffness."

This last part is what a lot of track guys have been starting to figure out. Take for example the (nominal) 255/35R19 tire mentioned in this thread, theoretically it should be 255mm wide, 255mm=~10". Therefore the wheel that it would produce its fastest lap times on is a 10" wide wheel. This has been proven with lap times for the past few years.

The same tire on say the stock 8.5" wheel is to have increased comfort (allows more compliance)... which is why Audi gave everyone a "narrow" wheel for the stock tire size.

[mmmkam]

this. those PSS 255 on a 9.5" is BARELY stretched. it will NOT affect your handling negatively in any way. 255 is perfectly suitable AND in the manufacturer's range for a 9.5" wheel.

+1. If you look at the tire specs on tire rack most 255 tires are speced out on a default of a 9" wheel, but will fit anything from a 8.5"-9.5" or even 10" wheel in some cases. Check the "measured rim width" which should be a 100% flat side wall. In those cases (just about all of them) where 9" is the measured rim width on an 8.5" wheel there will be a minor pull IN and at 9.5" or higher gives a minor stretch out. To your point depending on the wheel and tire combo the edge of the wheel will become more and more exposed the more stretch you put on the tire so be cautious around the curbs.

The pics posted above are a pretty accurate representation with the PSS. I posted some pics of mine at stock height with 9.5" rims and 255 Blizzark LM32 tires witch look slightly more stretched if you search.

My recommendation if you don't plan on lowering and like the stock look/profile of the tires is to stick with an 8.5" rim @ ET40 (close to the stock ET43) or at most 9". On mine even with the minor stretch of 9.5" and the flush sitting of ET 40 at that wheel size it just cries out for a drop to me visually although to date everyone that sees it and drools.

[IceSilverS4]

Thank you for the quote, very instructive !

... so Ill steal one of Emilio Cervantes' (Owner of 949 racing/NASA record holder at many tracks in California). He stated, "Lateral acceleration is only produced when one or both sidewalls are under tension. You turn the wheel, the contact patch lags behind...

[Skywagon]

Tire Rack web site says those tires will work on 8.5 to 10.0 inch wide wheels.

http://www.tirerack.com/tires/tires....XLV4&tab=Specs

[cspcrx]

157s information is spot on. One of the key words is the "slight" stretch. As with anything to much of a good thing can be bad. When I campaigned a car in SOLO2 seriously we would measure the width of the tire bead and match it to the width that is just slightly wider for the reasons mentioned above. You could feel the difference on turn in and through the slaloms.

You also need to consider what do you want to get out of your tire and wheel package. Is this setup going for max performance, looks or just to do what a normal tire does. When I do my setup, plan on 19x9.5 because I want some concave, I am going to go with a 265 tire. I want to protect the rim, incase I get to close to a curb. I personally also do not like the stretch look, just a personal choice.