Sagres74

I presently have 18" 996 turbo twists on my 89s4, with 295 series in the rear. Although I love the look, I've been looking to go to a smaller wheel for a while as I feel it'll look better, preferably 17". When performing some maintenance recently, I found evidence of rubbing in the rear pushing me to make a decision faster. The easy route is to replace the rears with a narrower tire (265) and keep the twists. However, bc I also discovered that my fronts are heavily worn on the insides, technically I'll have to replace all four tires. As such, I may as well replace both wheels and tires.

So, to the root of the question: Since I don't track the car, I'm leaning heavily to replacing the wheels with 17". However, I've found that many modern OE wheels (mostly Boxster and Cayman) are staggered even in the smaller 17" size. The wheels I'm partial to are 7"/ET55 and 8.5"/ET48. Understanding the basic advantages and disadvantages of wider tires in the rear, and also the 928 wheel history, what are your thoughts on simply using 7" all around. My initial thoughts: ability to rotate tires, tire warranty extended, better gas mileage.



Current set-up.


Wheels I'm interested in. 98636212606

dr bob

My two cents:

The 928 has a tendency towards under-steer in any aggressive street driving. Even with modern tire technology, it can readily use wider tires in the front. If you feel a need to go with a non-staggered wheel and tire set, look to wider fronts rather than narrower rears as the proper direction. The somewhat rare CS wheels were 16x8" in front and 16x9" rear. Not suggesting you run them, instead suggesting that you look for at least 8" wide fronts with something close to the CS-spec 68mm front offfset in your preferred diameter. You'll need spacers to run those wheels in the rear if you want to keep things square.

Porsche took advantage of the space in the rear wheel wells to support the extra performance available with the 32-valve S4, putting wider wheels and tires there to better deal with the added power.

Fix the ride height and alignment in front to get clear of the inner-rib scrubbing. You want to do that regardless of which wheels or tires you install. There's plenty of guidance here in the forum on what's needed to get a good alignment. Search is your friend. Get that front wear under control, and the option for 4-wheel rotations becomes a lot less important. With great alignment and very even wear across the tire faces front and rear, I just replace the fronts or rears as pairs when they come due.

I currently run 17" wheels 7.5" in front and 9" rear from an early-2000's 911. 225's in front, 255's rear. I'm migrating to Pilot AS3's from PS2's due to the potential for more colder-pavement driving here in the mountains of central Oregon. Good so far for the kind of driving I enjoy.

FredR

First of all if you have a problem with heel wear on the fronts you probably have something wrong with the toe alignment not the wheels/tyres- probably not enough toe-in - a classic problem if the car was not fully settled when aligned as further settlement post alignment causes the wheels to toe out as does lowering the car as happens when the front springs sag.

Unfortunately you do not say anything about your front wheel specs but if you can squeeze a 235 on the front and mate it with a 265 on the rear that is a good combination. However 996 wheels typically are wide on the rear and if fitting a 265 you must ensure the wheel supports that width. That being said no reverse spoke design wheel has the correct front offset [ET65] for your car and that makes them unacceptable to me but plenty of folks who do not push the envelope run with such offsets.

The wheel number you quote appears to be a 8.5 inch Boxster rear with ET48- it will work on the rear but useless for the front if that is what you have in mind.

Now if you can find a set of four Cup 1 design 9.5 inch rims with ET68 that is another proposition altogether but more probability of finding rocking horse droppings on Route 66.

The Forgotten On

235 width tires fit very well in the front and aid traction a lot compared with the original 7 inch wide fronts my S4 came with.

I'm using 18 inch Panamera rims which have an offset of 59 in the front, which is good, but not great. If you can find a set of 17s that have an offset higher than 60 you will be set.

The rims I use are staggered but I don't feel the need to rotate tires even though I daily the car.

Plus most drive their 928s so little the tires are past their best by date and should be replaced anyway long before tire rotation becomes an issue.

Petza914

The potential problem with going to a narrower rear is that your car might become more tail-happy. Aside for the width back there helping to get power to the ground, it also for a larger contact patch when cornering. Mid corner understeer is one phenomenon where the weight from the engine on the front wheels, turning angle etc overcome their grip factor and the car as a whole pushes through the corner, but snap oversteer in the rear is a very different phenomenon as the process of the car going through the corner loads the outside rear tire. If there's enough contact patch to overcome those forces, you don't notice a thing, but if there's not, that when you can get a loose rear (yes, pun intended because if it happens very quickly, not only will the car get loose, but so will you). If the car is never driven hard then this idea you're pursing is probably fine, but if you ever push it - mountain, club drive, etc, I'd stay with the staggered setup as the 928 doesn't have a lot of weight in the back to help plant the rear and the extra contact patch helps to do that.

danglerb

My two cents is that tire availability trumps wheel choice.

z driver 88t

To try to answer the question you asked, I would not hesitate to run 7s or 7.5s all around. I have several sets of wheels for my car (16-inch 944 CS wheels 7s and 9s, 16-inch manholes 16x7s all around, and 17-inch turbo twists 7.5s and 9s). I've driven the car at track days with the CS wheels and have done plenty of aggressive driving on each set.

As others have stated, the 928 will understeer at the limit. Wider rear tires just make the rear stick better. My car actually drives more neutrally with the four 16x7s with the front and rear tending to break away together although your initial perception is that the car will feel "loose" because you aren't expecting the rear to break away at all.

So, if you are really just looking for a good daily driver setup that allows you to rotate tires I would not see anything wrong with running 17x7s or 7.5s on all four corners. To get the look right and have the rear tires pushed out towards the edge, you'll want to experiment with the factory spacers from the earlier cars. My 928 uses a spacer on the rear with the 16x7s and depending on the offset you use you may also need a similar spacer and longer rear lugs installed.

Alan

IMO don't go from 18" -> 17" - you may regret it big time based solely on tire choices - where 17" options are disappearing fast. 17" vs. 18" has less visual difference to most than wheel style and wheel color - don't sweat the small stuff...? I happen to think the wheels you have look very good on the car as is

When the alignment is correct the tires should wear quite evenly - if they aren't that is where to look first. My GTS has no rotation opportunities, sizes (width) are staggered and the tires I run are unidirectional. No uneven wear issues (just rapidly wearing out whole sets of sticky ones). To Dr Bob's point - I did go wider at the front for better turning grip 235/45 R17 Vs. 225/45 R17 stock. I also increased the rears to 275/40 R17 Vs 255/40 R17 stock and also changed the brake bias valve to 33bar to get more balanced rear braking. My motivation was purely optimal grip for balanced handling but it gives you an idea about wear also. Whatever sizes you go to - a bit more upfront may help more in day to day driving. Wider rears are of value if you drive aggressively and/or have more HP/Torque available, if you drive relatively gently you won't notice any difference.

I do think a poor look on an obvious performance car is to have very skinny tires on it - to me that always looks very odd.

You could instead go with closer to stock width tries and trade grip & mileage ratings to balance out what you want. I'd keep the current wheels !

Alan

Ramp

Getting back to the original question of stagerred vs non . . .

I'm trying to figure out what to do with my new to me '86.5 which has the original 16's and needs new tires (that I don't want to buy knowing I would like to move to 18's.)

There is a nice set of new 18x8 Veloce 3.6's on ebay with 52 offset - I like the look but after reading many threads, am leaning towards what many have done and getting Panamera 18's F 18x8 R 18x9. Just not sure the best route. I don't care about tire wear and I'm not tracking but I do like spirited driving around town and twisties.

Advice ?

Petza914

Although those are pretty, et52 is not a good front offset for an 8" wide wheel on a 928 - out too far and a mid-corner bump will have the tire catch the fender lip - that's more of a 911 offset. The 928 needs closer to an et60 or even 65 if you can find them. The Panamera wheels people are using are an et59.

Ramp

Thanks Petza - I'll need to look into if those Veloce's would be good for my 911 3.2 - a nice change the the fuchs from time to time

I'll take a look for the Panamera staggered setup - unless something else pops up shortly.