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Why the split in wheel size front to back on newer 928's?

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Old 12-25-2006 | 02:23 AM
  #16  
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if you have "twitchy" issues with a 8" rim and wider rubber in the 255range, you have alignment issues. actually the wider tire makes things quite stable. when i put my 305s and 275s on the holbert car before the conversion, it drove like a dream. very stable over all surfaces, however, the sidewall stifness was a little harsh for a street car.

i went for a 225 and 245x50 rear mix on the 7s to get a little more meat in the rear. then, with the 7.5s and 9s, i did 235x45, 245x45 front and 255 to 275 rears. so ive pretty much tested them all. and on a street car (cup rims by the way) it was better each time i went larger. no trade offs. actually, the skinny tires just didnt do the platform justice. it pushed, had a more unstable ride and over all the larger tires no matter how i did it, always came through a positive.

mk
Old 12-26-2006 | 06:44 PM
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Originally Posted by jon928se
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.
Stock 8x16 flats and 245 wide rears came in '87 S4. They might have been option some years before but PET doesn't list them. In any case they were always joined together with 21mm spacers. Before S4, normal setup was 7x16 on all corners. 7x15 was stock in first few years in automatics, never in 5sp.

Reason why factory stayed in so narrow wheels and rubber was that original design didn't allow any wider. They have to be certain that all possible tire brands of selected size will fit without problems and have some margin to spare. Now people are using all margins and then some to fit 275 at front and 315 at rear etc. Factory can't do tight fits like that on production vehicle. Besided so wide street rubber wasn't even readily available when 928 was designed.
Old 12-26-2006 | 10:37 PM
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Snow chains too!

Originally Posted by Vilhuer
They have to be certain that all possible tire brands of selected size will fit without problems and have some margin to spare.
BTW, any idea why there were 'winter' rims? Was there some thought behind the shape of the rim?
Old 12-27-2006 | 03:33 AM
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Originally Posted by PorKen
Snow chains too!

BTW, any idea why there were 'winter' rims? Was there some thought behind the shape of the rim?
Part of my stack of receipts were for a set of snow chains from NAPA, but no sign of them or of them being used.

Wide tires and wet weather can be a real handful for most drivers. Fortunately my 60/40 Mustang has me trained to drive like granny if somebody spits.
Old 12-27-2006 | 04:39 AM
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Originally Posted by PorKen
BTW, any idea why there were 'winter' rims? Was there some thought behind the shape of the rim?
Winter wheels could be little easier to clean in factorys thinking. On GTS they were also narrower than stock versions to allow use of suitable sized rubber. Most important reason for different wheels was probably that coating on them is much stronger to have better durability against salt etc.
Old 12-27-2006 | 11:15 AM
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Danglerb, go to the top of the page and click on 928 Specialists. They have some factory wheels listed for 255s on all four wheels.
Old 12-27-2006 | 03:17 PM
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This one, BTW that site gives me errors directly, I search it via google.

Wheel - Factory "Design 90" Front 16x7
928.362.154.05
Price: $545.00

Too many digits.
Old 12-27-2006 | 05:36 PM
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Look for the Cup Racer set. Not suggesting you buy them, but look at the 17 x 9.5 size, and the 255 series tires fitted by the factory. Once you have ridden in a wide tire car it is hard to go back.
Old 12-27-2006 | 07:31 PM
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Originally Posted by Daniel Dudley
Look for the Cup Racer set. Not suggesting you buy them, but look at the 17 x 9.5 size, and the 255 series tires fitted by the factory. Once you have ridden in a wide tire car it is hard to go back.
BTDT went back.

Big wheels make me think of covered wagons, I like what sidewalls do for me.

What I will be watching for are a couple of somebody's 16x(whatever is one bigger than mine) take offs, expecting to get two nice wheels with decent 245 ish tires for maybe $300 if I am patient. Its not like old 16 inch 928 wheels are in great demand. Polished and/or chromed preferred maybe buy a whole set if staggered or 235 would work in the front on them.
Old 12-28-2006 | 12:47 PM
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Originally Posted by perrys4
Sounds like a guy trying to learn more about his car, very interesting and legitimate question. Wheres the problem?

You're right, this was one of danglerb's more reasonable questions, no need for me to have been snippy.



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