danglerb

Is there any special reason why the newer 928's have much larger size wheels in the rear than in the front?

Is it something I should be thinking about for my 83? (225/50/16 all around now on factory slots)

CaseyH

The newer models have wider rear fenders to make room for bigger wheels.

RyanPerrella

its called staggering

Its common practice on anything but compact cars, where they still suggest tire rotation. You cant rotate tires on sports cars, at least not front to back, and you cant side to side when you have directional tires as most here do.

jon928se

In the rest of the colonies staggering is something we do (unknowningly) following too too much beer.

I forget the early 928s (78,79) with 15" comfort fit wheels but didn't all 928s have 7" front and 8" rear until the SE/CS/89GT which had 8" front 9" rear then the 90GTon and GTS had 7.5" front and 9"rear.

Only GTS actually got wider rear fenders although the SE/CS/'89GT got the fender lips rolled.

It's Xmas eve here and all I can find in the tech specs books are Torque specs for mechanical braking systems? since when did 928s or any car since about 1930 have mechanical brakes??

Herman K

FYI, My first P-car a 1951, 1600 Super had all mechanical brakes!

94 GTS 5 spd

fabric

Although there was some discussion about tire size and traction, the first thing that comes to mind is the S4 had more power, so wider wheels/tires.

By putting more traction on the rear, it also gives the car an more docile handling demeanor, as it will increase any understeering characterstics at the limit. Some would say this isn't a performance enhancement.

I think, at least with the stock S4 wheels where you can see that the wheels are different quite easily, there's a very fine aesthetic quality to the change. Part of the reason I really like those wheels.

PorKen put 8"s all around, if I'm not mistaken. I'd say you're good with what you got, why don't you just drive it and enjoy it instead of worrying about every single little thing?

JEC_31

What fabric said, except the chiding.

perrys4

Sounds like a guy trying to learn more about his car, very interesting and legitimate question. Wheres the problem?

mark kibort

because porsche BLEW it with their design. off all the great things they did with 928, the tires and rim sizes wasnt one of them!

pretty stupid to have the 928 with its stock 240hp and 310hp in europe, to run on 225s!!!!! even the vets in 84 ran on 255s.

the body was all the same on all years. ever see a stock 928 from the rear, those tires look like 55mph compact spare on american cars!

the porsche 928 should have 245s up front and 255 to 275 in the rear minimum. when i had the 7" rims, I at least put a little larger tire in the rear. (245x50)

mk

PorKen

I did, with 245s all 'round on the '81. Very nice for handling, braking, but horrible for everyday driving. I didn't notice it so much until I swapped all four onto the 86, and the steering on the highway went from balanced to twitchy. You have to drive all the time, no slacking. I went back to 7"-8" on both cars, and they are much more pleasant to drive.

The '86 needed 245s on the rear. With the monster torque and first gear start, the rears would light up at nearly every stoplight, with my depleted uranium driving shoes. (Even before the cam advance, and EZF tweaks.)

Backspacing isn't the best on the S4 8"ers for the front. The 245's stick out a few MMs, and always looked a bit off.

I will need better wheels for the 86 in a few months - to show off the Brembos.

danglerb

Could be thats part of enjoying it.

I think I have 16x7 front and back, as I said 225/50/16 tires that have another year or so in them and plenty of tread, so I am just planning ahead.

I like the slots on the early cars, and I don't want more tire than I can use, but my wheels are stock and polished or chromed is appealing. So if I find a set of polished and or chromed wheels, that are maybe 7 in the front and 8 in the rear, but I think I will stay with 16". Tire to match that are maybe 225/50 front and 245/50 in the rear.

First car I owned with the stagger size was my 86 944T, and it just wasn't intuitive why a neutral 50/50 car like the 928 would have optimal tires with so much larger in the rear than the front. Since all the track guys are running the staggered sizes I assume its the best, but is it still neutral, what does it do?

Daniel Dudley

Less experienced drivers are more likely to overcook the throttle, and less likely to drive around a understeering front tire. They will go into a corner and feel the understeer and back off. If you come in a little faster, and balance with the throttle, all is well, and the wider rear tires are good for both.

I have been in a few cars running the larger diameter wider wheels, and I think they turn 928s into cornering beasts, bringing the handling into the modern era. 225s IMO work better on a car that is a little lighter, like a 944. With my 80 928 I started on 15 inch rims running 215s, and it was really old school, driving the slip angle all the time, front and back. Fun, but slow.

If you check out ebay you will see the 997 wheels as new takeoffs in the 18 inch sizes. Those are the ideal size and offset for a 928, and many come with new or near new N spec. tires. I think Hacker P has a set on his super OB. Looks like a deal to me.

Optimator

Hmm. Twitchy handling reported by Porken with S4 8” on the front may have to do with having a larger scrub radius from the wider/lower offset wheels.

I wonder if Porsche was planning on wider rear wheels all along, or if they were just going for that (as another Rennlister put it) 70’s Buick LeSabre look on the early cars. And how about the M415 option on the 83-86 cars that used 21mm spacers on the rear wheels to increase the track - was this option purely for aesthetic purposes? Was the goal to increase understeer?

danglerb

Could it be as simple as big tires on the front are a PITA to steer?

Or that driving style suits the staggered size? I am assuming the race guys put on whatever sizes that go around the track the fastest, but I am not that familiar with what those are for various cars. Seems like the back tires are always bigger for anything I can think of.

Donald

Not to pick a tangential nit, but staggering is usually a reference to different diameter tires from side to side, as is used in oval track racing. Never seen it refer to front-rear, but then there is no limit to my ignorance.