killav

"The rear tires are 245x45x16. I can't imagine a 40 series tire would make that big of a difference huh?"



Outlier,

Just remember, 245 is 245 is 245. This first number is the section width of the tire. A 245/45 vs. a 245/40 will only make the second tire's sidewall shorter. The width will be exactly the same, which is 245mm divided by 25.4(mm per inch) = 9.64 inches. This is the entire section width, not the tread width. With the natural "bow" of the side walls, this makes for a good fit on an 8" rim. I think you could squeeze a 255/40/16 (.65" less height than stock) or a 255/45/16 (.32" taller than stock) on your stock rim and you would be fine. But this will only add 10 mm to your section width. Not sure if that would be worth it to you. I did a search on tire rack and could not find a match for either size so I'm not sure if they would even be available.

Finally, make sure your current wheel studs are long enough to incorporate a spacer. If not, then it is a major operation from what I've heard to replace the wheel studs in the rear.

Art_Z

learned that the hard way. make sure you buy a spacer with studs or at least measure beforehand. my 19mm spacer was to thick to use the stock logs and its headed off to ebay shortly.

IcemanG17

I vote for new wheels-tires.......sure its expensive.....but 928's look so much better with 17-18-19" wheels......there are several aftermarket or factory porsche wheels that fit perfect without spacers.....I run the 18" Carrera III's (18x8 57mm front 18x10 58mm rear) with 235/40's in front and 265/40's in rear.....dropped right on with no spacers & no rubbing....of course a 265/35 or 285/30 would be better in the rear since 265/40 is a touch too tall....

morganabowen

I purchased my 19mm spacers from an online store that custom makes them here in Southern California. It took about a week to get them. The Spacers were $70 for the two rears and the a dollar apiece for the flat open ended lugs to bolt them to the hubs. Mine look at work great

neilh

Look for this style of spacer, they do not require you to extend the studs as the bolt on to the old ones and provide new studs.

bcdavis

I had a set of those, and they vibrated like crazy...

I found it easier to just upgrade to a used set of wider wheels.
I found some old BBS wheels on Ebay for $1000, and sold my old wheels for $500.

You can usually find a lot of stock 993/996 and other Porsche wheels out there,
since a lot of people upgrade to bigger custom wheels... Search the archives
to find out what will fit.

dfroelicher

Slightly off topic but does anyone know if the studs are aluminium or steel?

I know that the lug nuts are alum, I would like to switch to steel nuts but the guy at the tire place says that if the studs are alum the nuts will seize to the bolts and I'll be screwed. If that thinking applies to having two different metals then doesnt the studs have to be the same as the nuts?

Also if this is so, does any one know where to get steel studs and what the pitch and length need to be?

Jim bailey - 928 International

Studs are steel

Bret928

I’ve got the same issue on my 78' too. While I’m still addressing other issues I've got a set of 18x10” wheels in the rear sporting 265/35ZR18s and they need to be pushed out a little too.



However I was thinking that a 21mm spacer would push’em out to where they’d look good. But that would mean that I’d have to put in longer studs. Otherwise my lug nuts will only bite into about 9-10mm of threads vs. 25-30mm of threads that I currently have.

Brett928S2

Hi

Snap to above lollll....but mine is an S2

Same size wheels....same size tyres...but already taken my spacers off..

285/30/18 next change...or maybe 295 IF they will fit...

All the best Brett

PORSCHE 928 S2 AUTO V8 4.7 LTR 1986 IRIS METALLIC BLUE WITH X-PIPES ,RMB ,PROMAX CHIPS, KICKDOWN SWITCH.K&N.NITROUS KIT 150 HP.
PCGB UK 928 FORUM MODERATOR - Email managingdirector@pchealthcare.co.uk

Garth S

Outlier,
On my (ex) S4 with the same wheel/tire combo you have, I used 21mm bolt-on spacers to fill the wheel well. At 165mm rear ride height and with Konis, contact was not an issue ... if you have stock shocks, go with 19mm spacers, to gice a little more space on compression.

Re. spacers, I purchased a set of TUV approved from Germany - this is an area where quality counts! I'm certain equal quality can be purchased locally, but buyer beware ... we have no 'TUV' standards to be met.

Ispeed

The '89 GT spacers are 17mm and the bolt on kind with studs in them. Try those, I have a set on my S4.

tdelarm

18' rock...

Good God! Now I have to get 19”!!!!!!!

I remember not but a few years ago when I was about to put 18" on my shark, the Rennlist discussion that took place regarding how Porsche did not condone putting 18" on a 928 due to un-tested stress on suspension components or such. And how Porsche dealers should warn any 928 owners of that memo.

Glad to see that’s behind us.

morganabowen

Come on Tim, those are the old days Now people are going towards the 19" wheels

tdelarm

Good God...is it always about inches Are looks not enough in a mans life