Wheel Spacer Question

[slackc]

Hi,

This is my first post after recently acquiring my 2000 Carerra 2 (Australian delivered car)

I have taken off my wheels which have been upgraded at some point to 997 wheels. I have noticed that there is no wheel spacers and have had a bit of a look at what the original wheels might have been and have noticed that there is an offset difference After reading some of the other forums on this topic I have become quite confused. Is there someone out there who can help with what spacers (if any) should be used for this configuration. Also if spacers are used could you advise on the length of the lug bolts that need to be used with the spacers. Many thanks!

Front:

Wheel: 8J x18 ET57

Part No. 997-362-136-00 (997 Carerra III)

Tyres: 235/40 ZR18

Rear:

Wheel: 10J x18 ET57

Part No. 997-362-136-00 (997 Carerra III)

Tyres: 265/40 ZR18

I should add that there does not appear to be any modification to the suspension height. I shall be using this car as my daily drive and some weekend trips and don't plan to take it to the track. The current wheels don't appear to have rub marks or look to be rubbing anything on the inner side. Though one of the rear tyres is wearing slightly more on the inner side.

Edited March 25, 2013 by slackc

[amcleod1]

Congrats from a fellow aussie owner. Had mine now several years. Try the TSB section - you'll need to be a contributing member to view. If you aren't highly recommend you join.

Here's a link to one TSB on tyre and wheel sizes for 996.

http://www.renntech.org/forums/index.php?app=downloads&module=display&section=download&do=confirm_download&id=203

[slackc]

Thanks for the link, I have been able to decipher a few things and can see the following options. (or I may have it completely wrong, if I do someone please help!)

The front wheels should be OK but the rear ones are wider than allowable. [The current tyre sizes on the wheel suggest that the set came straight off a 997 as this is the tyre size specified for these wheels on 997 installation]

1) the closest configuration for my 2000 C2 is the 8J x18 RO 50/52 & 10J x 18 RO65 with the 5mm spacers per the approved summer tires data.

ie: with the spacers added equivalent to. 8J x 18 RO 47 (been closer to my wheels than RO 45) [front] & 10J x 18 RO 60 [rear]

Front

a 10mm spacer on the front would change the 8J x 18 RO57 to 8J x 18 RO47 which is as per spec, I will need to change the tyres to 225/40 ZR18.

Can someone advise which of the following I should do (the current tyres have about 15,000km tread remaining) or if there is any better advice; (front tyres have about 15,000km remaining, ~10,000 miles)

i) Change the tyres now and add 10mm spacer (or some other size spacer), what size attachment lugs should I use?

ii) add 10mm spacers (or some other size) now and wait till the tyres need changing in 15,000km time, or

iii) leave them as is for 15,000km, add the 10mm spacer (or some other size) and the correct tyres in 15,000km time?

Rear

My wheels are 2mm closer to the fender than it should be. (offset specified 60 [65-5], wheel is 58)

Firstly, the fender does not appeared to have been reworked, so I imagine this should be done?

Also, is someone able to confirm or give better advice to the following options in relation to the wheel?

i) I could machine 2mm from the rear hub face of the wheel (or from the mounting face of the brake disc rotor, which would need to be done each time the brake disc rotor is replaced) and that should take it to 60mm offset (the same as a 65 with a 5mm spacer) but this could damage the structural integrity of the wheel (or the brake disc rotor). The tyres need replacing now so I would replace with the recommended 285/30 ZR18,

ii) not worry about it as 2mm isn't much and install the recommended 285/30 ZR18 wheels and just keep an eye out for rubbing on the fender, or

iii) install tyres with a smaller tread width? If so, what tyre size and what is the consequence of using a non-approved size?

Edited March 25, 2013 by slackc

[Hilux2400]

I have a 996 2003 Carrera 2.

The standard offset for an 8J front is 50mm and for a 10J rear it's 65 without any spacers. I have tried 10J rears with an offset of 47 and they stuck out from the rear arches. The front will tolerate a width of up to 8.5J with an offset of between 50/52mm but an 8.5J is not in the handbook.

If you look in your handbook it will tell you the correct wheel size options for both 17" and 18" wheels with various widths and offsets.

With tyre widths it is important to get the profile right so that the rolling circumference of both front and back match as close as possible. For example:

265/35 on the back match 225/40 on the front. Once again refer to the handbook.

H

[Loren]

The narrow body GT3 (Mk2) uses a 40mm offset on front wheels that are 8.5J. So those would work fine too.

[slackc]

Thanks Hilux2400,

I had a look at the handbook and it has only one set of 18" wheels listed. front: 225/40 ZR18 on 7.5J x 18 RO 50mm and rear: 265/35 ZR18 on 10J x18 RO 65mm

Is the TSB for Approved Summer tyres, wheels & spacers in the link from amcleod1 above a revised version of the handbook approved wheel/tyre combinations? If so then I still have the queries as above which relate to the closest combination in this TSB (on page 4 of the TSB, the second row in the table front: 225/40 ZR18 on 8J x 18 RO 47mm (52mm with 5mm spacer) and rear: 285/30 ZR18 on 10J x18 RO 60mm (65mm with 5mm spacer).

Thanks all for your help

[slackc]

After talking this over with my local Porsche dealer and my independent Porsche mechanic and the Porsche dealers preferred tyre shop and armed with the TSB and handbook we decided on the following.

Change the rear tyres to 265/35 R18 ,they are due for change now

No need to flare the rear fender

Change the front tyres to 225/40 R18 at the next change (they are due in ~ 10,000km)

Add a 5mm spacer on the front when the tyres are changed on the front

This takes into account rolling circumferences etc. and gets as close as possible to an approved configuration as you can with these wheels.

Thanks all for your help. Chris