The perfect offset on 18s....zen...
 

If you could order entirely custom wheels for an S4, front and rear, with no spacers/fender mods..etc..

What would be the -perfect- offsets front/rear to squeeze in the perfect tire sizes?

Depends on desired size, usage, shock/spring setup etc.

I have 18x11 for all 4 corners for my car (track rims 14# each)

There is no perfect, its all subject to individual taste or lack thereof.

That said, maybe 8" and 10" with 245 and 295 tires. Ultimately I expect to find tires first, then a wheel and fender to fit. No point in liking this or that wheel if tires aren't easy to find.

An 8" back spacing for an 11" wheel will allow up to 305x18" tire to fit on the rear of an S4. A 9.5" front wheel with a 73mm offset will work with up to 275/40x18" up front.

Jim: Does that not mess with the front scrub angle/etc stuff too much?

Probly able to talk our race car sponsor outta set of wheels...just wanna know offsets.

Purely look good street use here...so you're on the right path.

The rear is not an issue. Front: 9.5" - 10", 70 - 75mm positive offset so you can easily run 265/35-18's.

Dan
'91 928GT S/C :eek: 475hp/460lb.ft

so... whats funny is I have been thinking about the same question for my Blue 89... So what I read in the answers so far is:

Rear: 11" wheel will allow up to 305x18"... what offset?
Front: 9.5" - 10", 70 - 75mm positive offset so you can easily run 265/35-18's

... and did they make an 18" cup rim? I really love the cup look on the 928...

Not OE. Mille Miglia made 18" Cup II replicas - that's what I have on the back of my GT (18x10 ET47). Problem is the matching 8.5" fronts are ET52 which is less than optimal. As such, I went with OE Cup II's in 17x9 ET70 for the front.

EDIT: As to the OP's question - I don't know if my setup is optimal, but I'm pretty pleased with it. Should work on a S4 without fender rolling.

I have a set of OEM 993 turbo twist hollow spokes in 10" & 8" with et 41 and 53. They are light, OEM and they really fill the wheel wells without the need for rolling the rear fender.
They are also for sale now that I got some Carrera III wheels

I'll be buying tires soon for my turbo twist wheels. I'm thinking 235 front and 275 rear. Don't want to go overboard.

9.5x18 et 68 front and 10x18 et 52 rear. You can run 265/35 fronts and 265/35 or 285/30 rears. No rubbing on a stock S4.

This is what I run on my GT:
9x18 et52 with 255/35 fronts
11x18 et65 (with 15mm spacer effectively making them et50) with 295/30 rears.
Stock'ish ride height, it doesn't rub anywhere with street driving - but it's a GT so fenders are rolled already. Sorry for low-quality cellphone pic, but that's the only one I have currently. :(

Edit: I would not recommend such an extreme offset on fronts if you're going for custom set of wheels, rather get ET70-75ish, as recommended.
But for rear 11" wide rims, it looks like ET50-55 is close to optimal.

Edit2: From the first pic, you could imagine that there's still quite a lot of space in rear wheel well - but that's not the case, check the second super-high quality pic. Tire fills the fender very nicely with little space to spare.

Stock up front is 65-70 and that is considered the prfect offset for the suspension geometry. Anything lower has always been a compromise due to lack of choices.

The rear is not as important.

If you are having wheels made, go for the most you can. If needed you can alway space them out but you cannot go the other direction once the wheels are made. Well you can, but it's not a good idea.

I have 4 sets that I run on my two cars - two for the '89 track car and two on the GTS.

For the '89, I have a set of 996 turbo hollow spokes on the front in 8" X 18, et 50. I run 255/35 Michelin PS2's or 245/40 Yoko AD08's there, and 295/30's on a set of 10" et 65 solid spoke 996 turbo twists on the rear. These are for driving to and from the tracks, and in case of rainy weather - on the track. A very small bit of tramlining on truck tire rutted macadam on the highway. For dry track, I have a set of 993 hollow spokes all the way around - 8" et 50 and 10" et 45. Tires are Michelin Sport Cup in 235/40 F and 295/30 R. Tracks have NO ruts!! Due to the lower negative offset of the rears, fender rolling is required.

For the street/highway only GTS, I have 18" Sport Design 2 piece wheels. Fronts are 9" et 70 (made by using spiders from the 7.5" front along mated with the 9" rear barrels from Boxsters). Rears are 10" et 65 from 911's. Tires are Michelin PS2's in 255/35 and 295/30. DRIVES GREAT on the highways and streets. At full lock in a slow turn on driveway, etc. there is a bit of scrubbing.
I also have the OE design 17" Cup II wheels for this car in the OE 9" et 65 rear, along with 8" et 70 fronts (OE was 7.5" et 65 fronts). The 8" are very rare wheels that were OE "winter" wheels on some 911's. This combination puts centerline of a wider front tire in essentially the same place as the OE 7.5" et 65 with 225/40 X 17 tire. I have Michelin Pilot Sports 295 R and 255 F on these wheels - rarely used, as I like the appearance of the 18" Sport Design so well on this car.

Gary

A couple posters use the term "positive offset" in error. You want NEGATIVE offset for your 928, moving the rim IN relative to the mounting face.