Randy V

235 front and 275 rear.

I won't say it again.

cali4sun

I'm interested to hear what works for best fit when you are done, as I'm about to do the same only difference is 18 x 8 front, same ET's front/rear, and same tire sizes as you noted..

'89 S4 GP White/Black
'76 912e Silver/Black

finally!

Thanks! I had typo errors in the sizes, fixed!

finally!

Sheesh, as if it was all not confusing and scary enough.. Found tires (could not find any 275/30/18 at TireRack or discount tires so no choice but to go with 285/30/18 for the rear)... and the price?

$666

YIKES! Evil...

White Lightnin'

Consider also the height of the sidewall... in some cases -even if the car is level, the visual factor of 'baloon sized' front tires will throw it off.

The following matches for circumference and visual effect as follows (by color):

Front:
225/40/18 = 90mm of sidewall (7"-8" wide wheel)
235/40/18 = 94mm of sidewall (8"-8.5" wide wheel)

Rear:
275/30/18 = 82.5mm of sidewall
275/35/18 = 96.25mm of sidewall (10" wide wheel)
285/30/18 = 85.5mm of sidewall
285/35/18 = 99.75mm of sidewall
295/30/18 = 88.5mm of sidewall (11" wide wheel)
295/35/18 = 103.25mm of sidewall
305/30/18 = 91.5mm of sidewall (11"-11.5" wide wheel)

In general terms, you want the width of the wheel to closely match the width of the tire without being wider (unless you're building a JDM ricer with wide wheels and narrow tires).

The 928 already has a nose-high ride level at factory specs -taller front tires will only magnify that visual disproportion.

ROG100

For the use of the DFW group I have a Tirerack wholesale account and providing you are able to pick up from 928sRus we charge cost no markup at all.

yardpro

wow..
that is an outstanding offer....

you want to open a branch up in the outer banks of nc....
i know just the guy there for the job...lol

finally!

AWESOME! PM sent!

FredR

A 285x30 will fit OK with a 60 offset and I suspect you will be OK even with a 65 offset.

I dare say the 225 will fit on a 7.5 inch rim but it is pushing it bit, I would have insisted on an 8 inch rim with 18 inch wheels. The 50mm front offset will fit OK and nicely fill the wheel well but I trust you appreciate that you will lose the negative scrub radius the steering was designed for. My experience of this is that on day to day driving you will not notice the difference but on a track you will probably lose out slightly compared to when your car is kitted with stock front wheels.

Regards

Fred R

finally!

Don't plan on tracking it ever so no worries there. Track duty will be left for next purchase possibly this year of a 1987-1989 911. Once I get the wheels and tires mounted, hopefully this weekend, will have an alignment done as well of course.

finally!

After much help from many here and ESPECIALLY Andrew O's incredible spreadsheet wheel fitment calculator only had one more thing to solve..

S P A C E R S

Of course this brought up a whole other issue, removing hubs, having to replace wheel bearings, etc., etc. So, after a few hours searching found some threads on Pelican and here related to the exact same wheels I have (Porsche Sport Classic II's) and spacers. Lo and behold Porsche makes a spacer which does not require installing new studs. Called local Porsche store and amazingly they had a pair of 17MM ones in stock which according the Andrew's spreadsheet will work!



Was lucky that one of the posts on Pelican even had a pic which included the part number! Picking them up tomorrow..



Many of you may already know of this solution but I did not so if duplicating something, apologies... I'm just happy to have found a solution which doesnt require a ton of work replacing the studs themselves!

Now of course paranoia is creeping in that someone here will post a reply saying NO NO NO!

Leon Speed

I think it's going to be close, but only one way to find out: try it!

finally!

Hopefully Andrews wheel fitment calculator is on target since when I input in to the spacers field in the spreadsheet anything from 8 to 23 it calcualtes it fits. 17 is toward the other end and in the middle between the 15 and 20 mm others recommended here.

Randy V

As long as you got the tire radius the same so your speedometer/odometer stay accurate you should be OK.

Drewster67

Is your car lowered? If so - 235 will not work on the front as it will rub.

I run 235/40/18 front (with rubbing) and 278/35/18 rears (no rubbing and NO spacers) - Nitto NT01's

ATP Rivas - Dunno the offset

Found these on tire rack

http://www.tirerack.com/tires/tires....um=735WR8DZ101

YMMV